1 results
Takedaite, a new mineral from Fuka, Okayama Prefecture, Japan
-
- Journal:
- Mineralogical Magazine / Volume 59 / Issue 396 / September 1995
- Published online by Cambridge University Press:
- 05 July 2018, pp. 549-552
-
- Article
- Export citation
-
Takedaite, Ca3B2O6, has been found in crystalline limestone near gehlenite−spurrite skarns at Fuka, Okayama Prefecture. It occurs as aggregates of granular crystals up to 0.8 mm long and 0.3 mm wide. The mineral is associated with nifontovite, olshanskyite, pentahydroborite, frolovite, sibirskite, calcite and an unidentified mineral, is white or pale gray, and has a vitreous luster. Takedaite is trigonal with space group of R
c, a = 8.638(1), c = 11.850(2)Å, Z = 6. The strongest lines in the X-ray powder pattern [d in A(I)(hkl)] are 2.915(100)(113), 1.895(75)(223), 2.756(61)(104), 2.493(44)(300), 2.044(21) (214,131), 2.160(19)(220), 1.976(18)(006), 1.549(12)(306). The Vickers microhardness is 478 kg mm−2 and the Mohs hardness 4.5. The density is 3.10(2) g cm−3 (meas.) and 3.11 g cm−3 (calc.). Wet chemical analyses give the values CaO 71.13%, B2O3 28.41%, ig. loss 0.14%, and total 99.68%. The empirical formula calculated on the basis of O = 6 is Ca3.053B1.965O6, with the simplified formula of Ca3B2O6.
