Abstract
Qingsongite (IMA 2013-30) is the natural analog of cubic boron nitride (c-BN), which is widely used as an abrasive under the name “Borazon.” The mineral is named for Qingsong Fang (1939-2010), who found the first diamond in the Luobusa chromitite. Qingsongite occurs in a rock fragment less than 1 mm across extracted from chromitite in deposit 31, Luobusa ophiolite, Yarlung Zangbu suture, southern Tibet at 29°13.86N and 92°11.41E. Five electron microprobe analyses gave B 48.54 ± 0.65 wt% (range 47.90-49.2 wt%); N 51.46 ± 0.65 wt% (range 52.10-50.8 wt%), corresponding to B1.113N0.887 and B1.087N0.913, for maximum and minimum B contents, respectively (based on 2 atoms per formula unit); no other elements that could substitute for B or N were detected. Crystallographic data on qingsongite obtained using fast Fourier transforms gave cubic symmetry, a = 3.61 ± 0.045 Å. The density calculated for the mean composition B1.100N0.900 is 3.46 g/cm3, i.e., qingsongite is nearly identical to synthetic c-BN. The synthetic analog has the sphalerite structure, space group F43m. Mohs hardness of the synthetic analog is between 9 and 10; its cleavage is {011}. Qingsongite forms isolated anhedral single crystals up to 1 mm in size in the marginal zone of the fragment; this zone consists of ~45 modal% coesite, ~15% kyanite, and ~40% amorphous material. Qingsongite is enclosed in kyanite, coesite, or in osbornite; other associated phases include native Fe; TiO2 II, a high-pressure polymorph of rutile with the αPbO2 structure; boron carbide of unknown stoichiometry; and amorphous carbon. Coesite forms prisms several tens of micrometers long, but is polycrystalline, and thus interpreted to be pseudomorphic after stishovite. Associated minerals constrain the estimated pressure to 10-15 GPa assuming temperature was about 1300 °C. Our proposed scenario for formation of qingsongite begins with a pelitic rock fragment that was subducted to mid-mantle depths where crustal B originally present in mica or clay combined with mantle N (δ15N = -10.4 ± 3‰ in osbornite) and subsequently exhumed by entrainment in chromitite. The presence of qingsongite has implications for understanding the recycling of crustal material back to the Earth’s mantle since boron, an essential constituent of qingsongite, is potentially an ideal tracer of material from Earth’s surface.
© 2014 by Walter de Gruyter Berlin/Boston
Articles in the same Issue
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- Thermodynamic approach provides insights into the aging process of biological apatite
- Effects of chemical composition and temperature on transport properties of silica-rich glasses and melts
- Speciation of and D/H partitioning between fluids and melts in silicate-D-O-H-C-N systems determined in-situ at upper mantle temperatures, pressures, and redox conditions
- Effect of oxalate and pH on chrysotile dissolution at 25 °C: An experimental study
- Gabbroic Shergottite Northwest Africa 6963: An intrusive sample of Mars
- Césarferreiraite, Fe2+Fe23+(AsO4)2(OH)2·8H2O, from Eduardo mine, Conselheiro Pena, Minas Gerais, Brazil: Second arsenate in the laueite mineral group
- Atomic structure and formation mechanism of (101) rutile twins from Diamantina (Brazil)
- Mathesiusite, K5(UO2)4(SO4)4(VO5)(H2O)4, a new uranyl vanadate-sulfate from Jáchymov, Czech Republic
- Comparison of metal enrichment in pyrite framboids from a metal-enriched and metal-poor estuary
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- Allendeite (Sc4Zr3O12) and hexamolybdenum (Mo,Ru,Fe), two new minerals from an ultrarefractory inclusion from the Allende meteorite
- Hutcheonite, Ca3Ti2(SiAl2)O12, a new garnet mineral from the Allende meteorite: An alteration phase in a Ca-Al-rich inclusion
- Infrared absorption spectroscopy of SiO2-moganite
- Kaolinite transformation into dickite during burial diagenesis
- Effect of clays and metal containers in retaining Sm3+ and ZrO2+ and the process of reversibility
- Solid solutions and phase transitions in (Ca,M2+)M2+Si2O6 pyroxenes (M2+ = Co, Fe, Mg)
- Further complexities of the 10 Å phase revealed by infrared spectroscopy and X-ray diffraction
- Solid phases of FeSi to 47 GPa and 2800 K: New data
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- Arsenate partitioning from ferrihydrite to hematite: Spectroscopic evidence
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- Qingsongite, natural cubic boron nitride: The first boron mineral from the Earth’s mantle
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- A high-resolution powder neutron diffraction study of the crystal structure of neighborite (NaMgF3) between 9 and 440 K
- Geothermometric study of Cr-spinels of peridotite mantle xenoliths from northern Victoria Land (Antarctica)
- Crystal chemistry of the ulvöspinel-qandilite series
- Quantitative models linking igneous amphibole composition with magma Cl and OH content
- Chromium solubility in perovskite at high pressure: The structure of (Mg1–xCrx)(Si1–xCrx)O3 (with x = 0.07) synthesized at 23 GPa and 1600 °C
- New Mineral Names
- Errata
Articles in the same Issue
- New data on lunar magmatic processes
- Thermodynamic approach provides insights into the aging process of biological apatite
- Effects of chemical composition and temperature on transport properties of silica-rich glasses and melts
- Speciation of and D/H partitioning between fluids and melts in silicate-D-O-H-C-N systems determined in-situ at upper mantle temperatures, pressures, and redox conditions
- Effect of oxalate and pH on chrysotile dissolution at 25 °C: An experimental study
- Gabbroic Shergottite Northwest Africa 6963: An intrusive sample of Mars
- Césarferreiraite, Fe2+Fe23+(AsO4)2(OH)2·8H2O, from Eduardo mine, Conselheiro Pena, Minas Gerais, Brazil: Second arsenate in the laueite mineral group
- Atomic structure and formation mechanism of (101) rutile twins from Diamantina (Brazil)
- Mathesiusite, K5(UO2)4(SO4)4(VO5)(H2O)4, a new uranyl vanadate-sulfate from Jáchymov, Czech Republic
- Comparison of metal enrichment in pyrite framboids from a metal-enriched and metal-poor estuary
- Chemistry of bone mineral, based on the hypermineralized rostrum of the beaked whale Mesoplodon densirostris
- Allendeite (Sc4Zr3O12) and hexamolybdenum (Mo,Ru,Fe), two new minerals from an ultrarefractory inclusion from the Allende meteorite
- Hutcheonite, Ca3Ti2(SiAl2)O12, a new garnet mineral from the Allende meteorite: An alteration phase in a Ca-Al-rich inclusion
- Infrared absorption spectroscopy of SiO2-moganite
- Kaolinite transformation into dickite during burial diagenesis
- Effect of clays and metal containers in retaining Sm3+ and ZrO2+ and the process of reversibility
- Solid solutions and phase transitions in (Ca,M2+)M2+Si2O6 pyroxenes (M2+ = Co, Fe, Mg)
- Further complexities of the 10 Å phase revealed by infrared spectroscopy and X-ray diffraction
- Solid phases of FeSi to 47 GPa and 2800 K: New data
- In-situ infrared spectra of hydroxyl in wadsleyite and ringwoodite at high pressure and high temperature
- Experimental and infrared characterization of the miscibility gap along the tremoliteglaucophane join
- A calorimetric and thermodynamic investigation of the synthetic analogs of cobaltomenite, CoSeO3·2H2O, and ahlfeldite, NiSeO3·2H2O
- Arsenate partitioning from ferrihydrite to hematite: Spectroscopic evidence
- Pressure-induced phase transitions in coesite
- Qingsongite, natural cubic boron nitride: The first boron mineral from the Earth’s mantle
- Phase relations in the system FeCO3-CaCO3 at 6 GPa and 900–1700 °C and its relation to the system CaCO3-FeCO3-MgCO3
- In-situ high-temperature emissivity spectra and thermal expansion of C2/c pyroxenes: Implications for the surface of Mercury
- Thallium geochemistry in the metamorphic Lengenbach sulfide deposit, Switzerland: Thallium-isotope fractionation in a sulfide melt
- Fluorowardite, NaAl3(PO4)2(OH)2F2·2H2O, the fluorine analog of wardite from the Silver Coin mine, Valmy, Nevada
- Correianevesite, Fe2+Mn22+(PO4)2·3H2O, a new reddingite-group mineral from the Cigana mine, Conselheiro Pena, Minas Gerais, Brazil
- Structural complexity of lead silicates: Crystal structure of Pb21[Si7O22]2[Si4O13] and its comparison to hyttsjöite
- A high-resolution powder neutron diffraction study of the crystal structure of neighborite (NaMgF3) between 9 and 440 K
- Geothermometric study of Cr-spinels of peridotite mantle xenoliths from northern Victoria Land (Antarctica)
- Crystal chemistry of the ulvöspinel-qandilite series
- Quantitative models linking igneous amphibole composition with magma Cl and OH content
- Chromium solubility in perovskite at high pressure: The structure of (Mg1–xCrx)(Si1–xCrx)O3 (with x = 0.07) synthesized at 23 GPa and 1600 °C
- New Mineral Names
- Errata