Archaeological Lithotheques of Siliceous Rocks in Spain: First Diagnosis of the Lithotheque Thematic Network

4.1 University of León Lithotheque (LegioLit)

Formed in 2004, the lithotheque in the University of León (UNILEON) contains samples of chert and other siliceous rocks from the western sector of the northern Iberian Peninsula (Herrero-Alonso et al., 2018, 2021). The collection records over 80 outcrops and a hundred samples of rock, only partially classified and described.

The lithotheque possesses spaces for storage, consultation, and a technical office. Its management is carried out by research and teaching staff in the university, who are also the directors of the project. The collection is accessible, on application, to consultation by external users. The ordinary services of the lithotheque, like allowing the use of characterisation equipment, are based on the shared resources of the university, such as scientific-technical laboratory services and libraries. The lithotheque is supported by extensive documentation, including photographs, records of the outcrops and the characterisation of samples, and reports of diverse analyses.

4.2 Lithotheque of Siliceous Rocks in the North-Eastern Iberia (LITOcat)

Formally institutionalised in 2002, this is housed in the Institución Milá y Fontanals for research in Humanities, of the Spanish National Research Council (IMF-CSIC, Barcelona) (Ortega & Terradas, 2014; Terradas et al., 2012). It contains a large collection of samples of siliceous rocks from the north-east of the Iberian Peninsula. The collection comprises about 5,000 rock samples, completely inventoried, with over 800 outcrops recorded. Accessible to external users, it has a storage space, management office, study room, and microscopy laboratory.

The collection is supported by extensive documentation that includes photographs of samples and outcrops, records of geological sites, preparations, and reports of the characterisation analysis of samples, maps, and a large catalogue of over 1,000 specialised publications about the regional geology. The lithotheque is managed by a scientific director and technical staff who work part-time in it. Its activities are funded by its own resources and partly by lending services to external researchers through the scientific–technical services of the IMF-CSIC (Terradas et al., 2023).

4.3 Lithotheque of North-West Iberia (University of Santiago de Compostela)

Created in 2020 at the University of Santiago de Compostela (USC), it contains collections of chert and other siliceous rocks (quartz and quartzite) from the north-west of the Iberian Peninsula (north Galicia) and other parts of the peninsula. The collection of over 100 samples, with about 70 outcrops recorded, is currently housed at the University of Oviedo. The initiative of founding the lithotheque came from the research carried out at the Palaeolithic sites of Cova Eirós (Triacastela, Lugo) and Monforte de Lemos Depression (Lugo), as well as other prehistoric sites in the region, and the need to determine the supply of siliceous rocks in a large area of crystalline substrate in which cryptocrystalline siliceous rocks rarely occur. The collection, only partially classified, is accessible on demand to external researchers not linked to its management, and also the associated documentation. The infrastructure includes storage space, a study room, and laboratories. However, it lacks funding and, apart from the responsibilities of the directors of the project, has no technical and scientific support staff.

4.4 Lithotheque at the Autonomous University of Madrid

Founded in 2000, the lithotheque in the Prehistory and Archaeology Department at the Autonomous University of Madrid (UAM) contains samples of siliceous rocks from geological formations in the centre of the Iberian Peninsula, in the area of the Autonomous Community of Madrid and, to a lesser extent, in other parts of the country. It possesses a little fewer than 200 flint samples with about a hundred geological outcrops recorded. The collection is open to the consultation of outside researchers in the case of a reasoned request.

The lithotheque possesses space for storage, laboratories, and consultation, shared with other educational and research resources and services in the department. Although it enjoys the ordinary services of university porters, security, and general administration, owing to its custody in a public educational institution, it lacks regular funding and technical staff. All the processes and tasks of management and maintenance of the collection are carried out part-time by the educational and research staff linked to it.

4.5 Lithotheque in the Prehistory and Archaeology Laboratory (University of Zaragoza)

The siliceous rocks lithotheque at the University of Zaragoza (UNIZAR) was created in 2015. It contains samples of siliceous rocks from sources in primary and secondary positions in Aragón, mostly from the centre of the region. Started in connection with a doctoral thesis, it contains a little fewer than a hundred samples with 40 outcrops recorded (García-Simón, 2018; García-Simón & Domingo, 2016). The collection is almost completely inventoried and described, labelled and stored in standardised containers that ensure its systematic classification. The storage space, management office, laboratories, and study room are shared with other educational and research services in the university.

The management of the lithotheque, which does not have its own funding and technical staff, is carried out by research staff. Although it does not provide a list of services, the collection is available for consultation by external researchers who may also request the loan or exchange of samples, the use of laboratory equipment, and technical support and guidance for their own studies and projects.

4.6 Lithotheque in the University of Barcelona (LithicUB)

The lithotheque in the University of Barcelona (UB) was formed in 2008 (Mangado et al., 2010; Sánchez de la Torre et al., 2014). It offers services of access and consultation of its collections and documentation, technical and scientific support for its users, and the mediation of access to scientific-technical services. It possesses spaces for storage and study with equipment for the characterisation of its samples. Its collections, only partially inventoried, include over 800 samples and records of nearly 200 outcrops, supported by extensive documentation that includes photographs, records of outcrops, maps, and reports of characterisation analyses. The lithotheque is managed by research and educational staff, as well as the regular collaboration of external researchers, but lacks technical staff. It is the only lithotheque in Spain that uploads its collections online (https://www.lithicub.net). The samples come mostly from the north-east of the Iberian Peninsula, but also from other regions in Spain, Portugal, and France, and also from Israel and Jordan.

4.7 Lithotheque at the IPHES (LithIPHES)

Established in 2017, the lithotheque in the Catalan Institute of Human Palaeoecology and Social Evolution (IPHES) in Tarragona contains samples of siliceous rocks from geological formations in the southern part of Catalonia and, in smaller numbers, from other parts of the Iberian Peninsula. It consists of about 300 rock samples from a total of 80 outcrops recorded and inventoried. It also contains about 1,000 samples from other parts of the Iberian Peninsula and North Africa, partially inventoried. The infrastructure includes shared storage spaces, a management office, laboratories, and study and microscopy rooms, as well as the equipment and staff in the technical services for geological preparations in the Institute.

The directors and technical staff work part-time in the lithotheque, with the occasional support of other specialised technical staff. As it is held in a research centre, it benefits from the common administration and maintenance services, among other advantages. It allows access and consultation of its collection, the loan and exchange of samples, use of laboratory equipment and instruments, and scientific and technical support to external projects.

4.8 Lithotheque of Flint and Siliceous Rocks of Interest for Prehistory (University of the Basque Country)

The repository at the University of the Basque Country (UPV/EHU) is probably the largest in terms of the number of samples, outcrops of siliceous rocks, diversity of sources, and geographic scale of all the flint lithotheques in Spain. Founded in 1997, its collections include samples of flint from geological formations in the Basque–Cantabrian region and adjacent areas in Iberia and France (Tarriño, 2006; Tarriño et al., 2015), which are covered exhaustively, as well as other Iberian regions, including large areas in communities of Castilla-La Mancha, Valencia, Murcia, and Aragón.

The lithotheque is pending its inventory and documentation, which does not allow access to external researchers. It possesses storage space, study rooms, and access to laboratories and equipment for optical microscopy. It is managed by its scientific directorate without the assistance of other staff. Without its own funds for its functioning, the collections continue to grow and are documented regularly through other research projects in which the scientific staff linked to the lithotheque participates.

4.9 Lithotheque of the University of Cádiz (LitUCA)

Created in 1995, the lithotheque at the University of Cádiz (UCA) contains samples of flint and, in smaller quantities, of other siliceous, sedimentary, metamorphic, and igneous rocks from the southernmost regions in the Iberian Peninsula (provinces of Cádiz, Málaga, and Gibraltar), as well as from Ceuta and northern Morocco (Domínguez-Bella et al., 2016). Its collection, which comes to nearly 5,000 samples, is only partially catalogued and documented (Ramírez-Amador, 2019). The lithotheque is housed in a geology laboratory (UGEA-PHAM; in the Department of Earth Sciences), and its management and maintenance are carried out by the scientific staff of this laboratory. It is accessible to external users, although that and other services are not included in a formal catalogue of the public services of the institution. The lithotheque is supported by extensive documentation that includes photographs and records of sites and sample descriptions. Owing to its location in a science faculty, it enjoys access to less usual educational and laboratory resources, like a university geology museum.

4.10 Lithotheque at the University of Valencia (LITOLABUV)

The lithotheque at the University of Valencia (UV), created in 1998, holds a collection of siliceous rocks and smaller numbers of other lithologies (limestone and quartzite) from the centre and south of the region of Valencia, which covers geological units at the eastern end of the Iberian Range (Castilian–Valencian branch, in the province of Valencia), and the Baetic Range (Pre-Baetic of the Outer Zones, in the province of Alicante). A large part of the collection has been subject to archaeometric characterisation for some archaeological case studies (Eixea et al., 2021; Ramacciotti et al., 2022).

Its collection, which is not inventoried, comprises fewer than 100 rock samples with about 20 outcrops documented. They are stored in boxes and on shelves in the research laboratory in the Department of Prehistory, Archaeology, and Ancient History in the UV. Without a list of services, it allows access to the collection and its documentation to outside researchers on application to the lithotheque management team. Although it is held in a university laboratory, it has no specific staff or funding for its improvement and expansion, and its management and documentation are attended to by the research staff linked to the project.

4.11 Rock and Minerals Lithotheque at the University of Oviedo (LitoMinAst)

The lithotheque at the University of Oviedo (UOV), founded in 2006, contains two collections: one of siliceous rocks and other lithologies (LitoAst) and the other of minerals (MinAst), mostly from Asturias and the central Cantabrian region, and to a lesser extent, from other areas in the centre and north of Iberia and SW France (Duarte et al., 2023).

Held in a university centre, the lithotheque has use of storage space, study rooms and a laboratory, with microscopy equipment and furnishings (shelves, filing cabinets and standardised containers for the samples and preparations, among others). The collection has almost 2,000 samples partly georeferenced and catalogued, and supported by corresponding documentation, including cartography, photographs, records describing outcrops and petrological preparations, analyses reports, and geographic information of sites and geological units of interest. Although without a list of services, the lithotheque can be accessed by external users and allows the exchange and loan of samples. It lacks technical staff for its management, which is carried out by the research staff associated with the project.

4.12 Geoarchaeological Flint Lithotheque at the University of Granada

The flint reference collection in the Prehistory and Archaeology Department at the University of Granada (UGR) is the consequence of several doctoral theses, either aimed at documenting the procurement of raw materials at particular sites or focused on the documentation of the sources of the most important raw materials used in the region in prehistory and in historical times (Contreras-Cortés & Dorado-Alejos, 2018). This has permitted the identification of the main types of flint utilised in prehistory and their archaeometric characterisation.

It currently contains about 500 geoarchaeological samples, all of which are sorted according to their provenance, having collected specimens from the main varieties of sedimentary microfacies represented in the outcrops. The collection is housed in the store rooms of the department laboratories, and can be consulted on application to the scientific managers of the lithotheque, since it lacks specific technical staff. At the same time, the Archaeometry Laboratory (https://sites.google.com/view/laboratoriodearqueometriaugr) allows the use of scientific instruments for observation and documentation of the collection.

4.13 Lithotheque at the University of Alicante

Initially formed in 2007 and built up in the frame of the research of a doctoral thesis, the collection at the University of Alicante (UA) contains samples of siliceous rocks and other lithologies (igneous, metamorphic and sedimentary rocks) from the south of the region of Valencia and the north of Murcia, in the south-east of Iberia (Molina-Hernández et al., 2014, 2016, 2018).

The lithotheque is stored temporarily in rooms at the UA and lacks its own space, equipment and instruments. Its management is carried out by scientific staff connected to it. It is currently not accessible to outside users. The collection is only partly catalogued. It includes hand samples and petrographic preparations of siliceous rocks from a homogeneous geographic and geological zone (the eastern end of the Baetic range), exhaustively surveyed. The documentation of the lithotheque includes, in addition to the records, reports, and photographs, the description and full list of the flint types in the region and digital geographic information about the outcrops and the geological units they belong to. Without any regular funding or administrative staff, its activities are financed by other research projects.

5.1 Geography and Territorial Scope

The lithotheques were created wherever there were consolidated research groups that then, and still today, carry out full programmes of archaeological fieldwork. The geography of the lithotheques, therefore, faithfully reflects the map of the areas where fieldwork has been performed (Figure 1).

Figure 1

Location of the thirteen Spanish lithotheques and geographical scope of their collections.

Most of the lithotheques are based in universities and public research centres distributed along the geographical periphery of the Iberian Peninsula in Spain. They are scarce in the interior and the west of Iberia, where the geology is mostly crystalline and provides few siliceous rocks of chert type.

As a result of their establishment with disparate objectives and at different times, without adhering to an initial joint plan, the geographical scope of the provenance of their collections varies and overlaps in their areas of interest. Without having assessed the effects of the duplication of certain geological formations and outcrops, it is to be expected that when the data from the different collections are cross-referenced, this will result in a better understanding of the phenomena under consideration and a richer and more varied sampling.

Obviously, the repositories with the widest geographic scope (UPV/EHU and IMF-CSIC) are also those with the largest collections.

5.2 Management Staff and Technical Support

All the lithotheques are managed by research staff, although in all cases the responsibility was attributed without a formal appointment. The informality of the director’s position and even the perception that it was not necessary led to three groups (UNILEON, UCA, and UAM) to state that there was no director and a fourth (UV) to specify an infrequent joint direction.

In each lithotheque, the directors were the people who, while working in research and education, took part in forming the collection and assumed its conservation, improvement, and growth (e.g., UNILEON, UOV, or UCA). Whatever the time they devote to the lithotheque, the scientific staff carries out administrative and management tasks, negotiate with other agents in the organisation structure of the centres hosting the collection, obtain material resources and funding for its maintenance, and participate in activities for dissemination, communication, and external relations.

While all the lithotheques stated that they were run by either personal or collegial management, only three possess full-time (IPHES and IMF-CSIC) or part-time (UB) technical staff for the lithotheque, although none of them on a permanent basis. In the three cases, these are the lithotheques with the greatest provision of other resources and which have advanced most in the development of their respective projects (e.g., the publication of the catalogue of their collection: UB, or in regulating the provision of services to external users: IMF-CSIC).

Among other tasks, the technical staff is responsible for the inventory and cataloguing of the collection, its conservation and enlargement, maintenance and care of the facilities, technical equipment and instruments, documentary and archive management, attention to users, and participation and support in research projects and training programmes for new research staff (IMF-CSIC).

Together with a director and technical staff, six of the thirteen lithotheques (UNILEON, IMF-CSIC, IPHES, UB, UNIZAR, and UOV) stated that collaborators were linked with their respective projects in one way or another. In some cases, they were technical staff in other areas of the institutions (IPHES), or other research or teaching staff from the institution (UNIZAR and UB) or from an external institution (IMF-CSIC).

In all six cases, the collaborators included professionals who provide skills that the management team of the lithotheques deem important for an improved service (e.g., the advice of external geologists, IMF-CSIC). Their link to the project, although informal, is supported by the benefits and the learning that both receive through their mutual collaboration.

5.3 Facilities and Equipment

All the lithotheques possess a space and facilities to hold their collection and attend to the everyday needs of their management. To a greater or lesser extent, they all share rooms and resources with other services and facilities in the institutions (e.g., laboratories, classrooms, and teaching offices), and in several cases, they are fully housed in such facilities (e.g., UAM, UOV, and UCA). Only the lithotheques with large and voluminous collections that have acquired greater institutional recognition in their centres possess their own facilities separate from other activities (e.g., UB and IMF-CSIC).

The facilities of the lithotheques include storage space (nine of the thirteen lithotheques), offices for the team managing the collection (in five cases), study rooms (eight), laboratories for processing, recording, and characterising the rock samples (seven) and other rooms (two). The average size of their facilities is 59 m², with a minimum of 4 m² inside a laboratory (UAM) and a maximum of 180 m² (IPHES).

The stores and their furniture (shelves, containers, etc.) are adapted in each case to the available space and the size of the collection. Sometimes, a simple cupboard in a laboratory or study room is enough (e.g. UCA, UOV, or UAM). Only three repositories (UNILEON, IPHES, and IMF-CSIC) are in separate store rooms with controlled access for the secure custody of the collection. They all use standardised containers and inert packaging to store the different types of samples (Figure 2).

Figure 2

Storage cabinets for the collections hosted on the IPHES (left), UB (centre), and IMF-CSIC (right) lithotheques.

In general, offices used by scientific and technical staff are equipped with basic furniture and services (telecommunications, air conditioning, etc.) for their correct functioning, in the same way as the rooms for the consultation of the collection. Most of them also have access to laboratories for the initial processing of the rock samples, their recording and characterisation, generally shared with other services in their respective centres.

5.4 Technical Equipment and Instruments

As they carry out similar functions, the technical equipment and instruments in the lithotheques tend to be similar. The ordinary tasks of cataloguing, describing, and consulting the collection, which in most cases consists of rock hand samples and thin sections, require the use of optical microscopes such as binocular and petrographic microscopes. Half the lithotheques (six out of thirteen) have their own equipment, while the others share equipment with other services and laboratories in their centres.

They all have use of other equipment, such as instruments to test the hardness of materials (IMF-CSIC), gemological drills (UPV/EHU), balances to weigh samples, digital microscopes, light boxes and cameras, as well as small equipment for fieldwork, such as compasses, handheld GPS receivers, hammers and chisels, and individual work protection equipment.

The needs of specific laboratory equipment for the preparation of samples are met by external services, either in-house or outside the institution. Only two lithotheques (IPHES and UCA) have such equipment (for sawing, polishing, and grinding rocks, as well as thin section preparation) which is shared with other analytical services in the centre.

5.5 Collections

Collections of rocks are the reason and heart of the lithotheques. Even though the lithotheques that participate in the project are repositories of sedimentary siliceous rocks, nearly half of them also include other lithologies (UNILEON, USC, UPV/EHU, UOV, and UCA), including several types of igneous, metamorphic and sedimentary rocks, siliceous or not, and even metal minerals (UOV) of common use in the regional prehistory.

However, despite sharing the same basic purpose, they vary greatly in the size of the geographic area of their provenance and the state and extent of their inventory.

All the collections include large blocks, hand samples, and thin sections preparations, and most of them (in nine cases) also contain samples of powder created by grinding samples for analyses. The number of hand samples in the collections ranges from 100 or 200 (e.g., UAM, UV, UNIZAR or USC) to nearly 5000 (UCA and IMF-CSIC) (Figure 3), although those figures are only definitive when the inventory has been fully or nearly completed. Only two lithotheques have fully or almost inventoried their collections (IMF-CSIC and UNIZAR), while the rest have finished half the task (four cases), only started it (five), or not even started (two).

Figure 3

Number of samples from participating lithotheques in the Network based on the data reported by each one. The circles indicate ranges up to 500 samples, from 501 to 1,000, from 1,001 to 3,000, and more than 3,000.

The variable degree of cataloguing the collections is largely due to the different details in the descriptions of the samples. Thus, some collections only partly catalogued are also the ones in which the samples are most exhaustively described (e.g., UB, IPHES or UA), while in some of the collections that are better inventoried, the descriptions are briefer (IMF-CSIC).

The lithotheques with the largest number of samples have also documented the most outcrops. These again vary widely, from as few as 50 outcrops (UNIZAR or UCA) to over 800 (IMF-CSIC), and altogether, the repositories have recorded over 1,600 localities.

Whereas most lithotheques only record the outcrops that have been visited and where samples were taken for their collection, others (IMF-CSIC) list a large number of sites where siliceous rocks outcrop, according to specialised literature, but which may not have been visited. In any case, for those cases where the study areas of different lithotheques overlap, it will be necessary to consider the number and type of outcrops sampled, as well as their significance in the characterisation of the different geological formations. It will then be possible to establish strategies aimed at studying and sampling deficient or poorly studied areas.

5.6 Documentation

As well as the collections of rocks, lithotheques gather extensive and diverse documentation that might include descriptive records of sites and geological outcrops, reports on the results of analyses for the characterisation of samples, photographs, different kinds of diagrams, and publications by themselves or others. All this information may be regarded as metadata that documents and describes the collections, and whose management is probably one of the biggest challenges for the lithotheques.

5.7 Work Processes

As in the case of the equipment, all the lithotheques carry out similar tasks to gather and organise their collections and provide services.

The usual tasks include recording the natural sites where siliceous rocks outcrop, fieldwork to acquire samples, the initial processing and inventory of them, their characterisation, storage, and publication of the data. The time devoted to this work is only occasional, except in the lithotheques with staff assigned to their management (IPHES and IMF-CSIC). The director and scientific staff also carry out various administrative jobs.

None of the work processes follows a formal protocol, although several lithotheques say that they are working on these (e.g., protocols for documentation of outcrops, georeferencing spatial information, and recording the metadata of photographs).

The acquisition of hand samples of rock is the basic work of all the lithotheques. This implies locating and visiting the natural outcrops of flint, their documentation, which is usually done with standardised forms (Mangado, 2004; Tarriño & Ulibarri, 1992; Terradas et al., 2006), and collecting the samples. The outcrops are located by previously georeferencing the sites described in regional geological literature (IMF-CSIC) and/or field surveys to locate, record, and sample new sites (UB, IPHES, and IMF-CSIC).

The hand samples obtained in the field are generally recorded by referring to the outcrop or site of their provenance, and only occasionally in smaller sections or stratigraphic descriptions of them (UPV/EHU).

The documentation and description of the collections begin with their inventory. The lithotheques that were based mainly on archaeological and university research projects (UB, UNILEON, and UAM) benefited from fuller characterisation, as that was generally carried out and largely funded in the framework of those projects.

Finally, part of the work of the lithotheques includes the publication of data as well as goals, methods, and scope of projects. Only in one case (UB) has the partial inventory of its collections been published, in addition to other dissemination works on these projects.

5.8 Catalogue of Services and Facilities

All the lithotheques cover a full range of services that include access and consultation of their collections (eleven out of thirteen), allowing the use of equipment for their characterisation (ten), technical and scientific support and advice to users (ten), loan and exchange of samples (four) and mediation for access and contracting services to external users (four).

The services are generally offered as a self-service system with no special restrictions, which implies full access to the collections and their documentation without any other limitation than citing the lithotheque in any study that derives from the consultation.

Only in one case (IMF-CSIC), some services of the lithotheque are included in the catalogue of scientific-technical services of the institution and subject to administrative regulations and the payment of a fee to the centre holding the collection. Similarly, only one lithotheque (IMF-CSIC) lays out in internal documents the list of its services and the commitments and obligations it acquires with external users when it provides them, even if those documents have not been approved administratively in alignment with the usual catalogue of public services.

5.9 Other Services

In the same way as they share other resources (affirmative answer from four of the thirteen lithotheques), the collections and their users benefit from multiple services provided by the public centres and institutes in which they are housed.

This includes the support of administrative services for hiring staff, acquiring equipment, and the financial management of projects and services linked to them, porters and security personnel that enable the access and identification of users, communications with external parties and postal costs, cleaning and maintenance of the facilities, and others, especially the assistance of information technology technicians and library and communications staff.

The lithotheques are able to resort to the infrastructures and IT services of their respective centres for support and assistance to ensure their development. This includes, among other aspects, storing databases and document management systems on the centre’s servers, technical support for their installation and maintenance, and mediation with providers and developers of external digital services.

Library services and documentation centres (map libraries, repositories of digital publications and unpublished research projects, etc.), whether or not they are mediated by the lithotheque, are essential for their users who often need to consult published documentation as well as to view the collections and use the available equipment.

Together with the documentation services, some lithotheques offer more unusual services, such as access to palaeontological collections (UOV), other collections of rocks for educational or museum purposes (UCA) and laboratories and experimental artefact collections (UAM, UGR, and IMF-CSIC).

6.1 Are Lithotheques Reference Collections?

The collections of rocks in the archaeological lithotheques match the definition of a geological collection given by the United States Geological Survey (USGS): ‘a set of geological specimens that have been brought together on the basis of some common characteristic’ (GMRWG, 2015). The common characteristics here are their lithology (siliceous rocks) and the geographic area of their source (Iberian Peninsula).

The USGS establishes the basic distinction between research collections, which contain geological samples obtained in the framework of a research project, and reference collections, which are defined as containing samples of a distinct nature that provide an objective standard against which other samples are compared for their identification.

Both are active repositories if they continue to add materials and are generally in use in scientific research programmes. Or they are resource or legacy collections, which are finished projects even though they may certainly continue to be of use for scientific investigation. An example of the latter type is the large collection of siliceous rocks made by Dr M.A. Bustillo, a former researcher in the CSIC, which is currently deposited in the Archaeological and Palaeontological Museum of the Community of Madrid, in Alcalá de Henares.

The lithotheques belonging to the Network are all active research collections, although strictly speaking, they are not reference collections. For that, they would need to contain in their collections samples of every kind of flint that displays the standard proposed for its definition, which none of the collections have achieved or aims to do.

Although they do not single out the samples with reference value in their collections, progress has been made in the formal definition of some types of siliceous rocks used widely in their regional geographic areas, through their complete petrographic characterisation and monographic publications (Bustillo & Pérez-Jiménez, 2005; Fuertes-Prieto et al., 2014, 2016; García-Simón & Domingo, 2016; Gómez de Soler et al., 2020, 2023; Herrero-Alonso et al., 2016, 2021; Lozano et al., 2010; Molina-Hernández et al., 2018; Morgado et al., 2011; Ortega et al., 2016, 2018; Sánchez de la Torre & Mangado, 2016; Tarriño et al., 2007, 2013).

6.2 From Scientific Collection to a Lithotheque: The Offer of Services

As explained above, what distinguishes a scientific collection of rocks from a lithotheque is the provision of services to external users. However, it is not enough to merely declare the aim of moving from one category to the other. Forming a lithotheque implies fulfilling at least two conditions: (a) a degree of formalisation of the services that will be delivered; and (b) the provision of the means for its implementation and maintenance.

However, most lithotheques in the Network originally formed their collections to support other research projects, not to provide a service. Among other aspects, this determines absolutely and for each collection, the geographic scope and area of the provenance of the samples (often from single sites, with no geographic continuity or prior selection depending on their interest for the archaeological research), their lithology (flint and other rocks), the type of geological deposits in which they are located, and the form of sampling.

In turn, this implies directing the fieldwork routine and acquisition of materials towards surveying and recording new geological sites: the potential sources of lithic raw materials (for their definition, see Terradas, 2001), with the difficulties that entail. This usually results in an unequal and irregular vision of the offer of raw materials in the region; however, that does not signify that they fail to satisfy the goals of the projects behind the fieldwork.

In this situation, the collections in some lithotheques tend to grow with the acquisition of new rock samples from the different areas in which the researchers linked to the lithotheque carry out their investigations. Some examples are the lithotheques in the UPV/EHU, UAM, and UB, which are institutions with a long history in the training of new research staff. In this sense, collection management is a great chance to train new researchers and help them reach their academic goals, like master’s or doctoral theses. These activities contribute to improving contextual information about the collections and how this can be used in archaeological research. Without a doubt, the role of PhD students is an aspect that should be highlighted and could contribute to the greater institutionalisation of lithotheques.

Since the study of archaeological assemblages is the reason that encourages the collection of geological references, it benefits from the exhaustive description and petrological characterisation of part of their collections, while for the same reason, a complete inventory is not their priority. This is the case, for example, of the collections of the UCA, UNIZAR, and UB.

The means to attend to the storage and consultation of the lithotheques were similarly established to satisfy the needs of other research projects. It must be admitted, as remarked above, that the opportunity of offering access to the collections by external users only emerged later. That is when the shortcomings for the provision of services appear, stemming in part from the difficulty of implementing the necessary infrastructure, equipment, and technical personnel, being a common feature of all lithotheques. As mentioned in the characteristics of the different lithotheques, these services are very uneven and often require recourse to services provided by other departments or laboratories within the same institution.

Even so, the provision of services by lithotheques requires their definition and at least some formal guidelines that guarantee the rights of the users of those services. In turn, the institutions hosting the lithotheque should furnish the means for the services, which presupposes their acknowledgment of it. Paradoxically, that acknowledgement is currently the greatest deficiency of Spanish archaeological lithotheques.

6.3 Deficient Institutional Involvement in the Lithotheques

The replies to the survey sent by the managers of the Spanish archaeological repositories reveal a common perception of the informal nature of the service they say they provide, which, apart from some exceptions, are not included in the usual list of services accessible to outside users and lack formal service charters (for public service charters in Spain, see Torres, 2005).

The institutions where the collections are housed are themselves unaware de iure that they possess them, as they do not appear in the inventories of their property because they are usually the consequence of research projects and not a formal acquisition. Even their public ownership is sometimes questioned, as the results can be perceived as the outcome of individual effort. It is obvious that, as occurs in many cases, if the institution is formally not aware that it provides a service, it will not dedicate any resources to its maintenance. It can therefore be understood that several lithotheques are kept at the expense of other services or facilities, and they all lack stable administrative staff and the regular assignment of a budget for their activities.

It is up to each collection to define its objectives and the means that it should be furnished with, adapted to the possibilities of its institutional situation. Housing the lithotheque at the expense of established services, such as laboratories and classrooms or university museums, may often be the best strategy and the quickest and most efficient way to consolidate it.

We certainly cannot demand that all the lithotheques follow the same route to the provision of services. Scientific collections correctly stored and documented will always be of use in research for the archaeologists who gathered them and others.