Macquartite

General Information: Chemical Formula:Pb3Cu(CrO4)(SiO3)(OH)4·2(H2O) Composition:(Molecular Weight = 981.28 gm)Chromium 5.30 % CrCopper 6.48 % CuSilicon 2.86 % SiHydrogen 0.82 % H Lead 63.35 % PbOxygen 21.20 % O  Empirical Formula: Pb3Cu(CrO4)(SiO3)(OH)4·2(H2O) Environment:Encrusting dioptase. IMA Status:Approved IMA 1979 Locality:Mammoth mine, Tiger, Pinal County, Arizona, USA. Name Origin:Named for Louis Charles Henri Macquart (1745-1803), French chemist who brought to France from Russia the samples of crocoite in which the element chromium was discovered.Physical Properties: Cleavage:[100] Good Color:orange. Density:5.49 Habits:Euhedral Crystals - Occurs as well-formed crystals showing good external form., , Hardness:3.5 - Copper Penny Luster:Adamantine Streak:light orangeMore details...

Pb3C (CrO4)SiO3(OH)4 2(H2O)