Calcite, Galena, Pyrite, and Quartz Assemblage
Image: <bdi><a href="https://www.wikidata.org/wiki/Q56247090" class="extiw" title="d:Q56247090"><span title="mineral collector and dealer">Robert M. Lavinsky</span></a></bdi> (CC BY-SA 3.0)
Mineral NameCalcite, Galena, Pyrite, and Quartz Assemblage
Chemical FormulaCaCO3 (Calcite), PbS (Galena), FeS2 (Pyrite), SiO2 (Quartz)
Mohs Hardness2.5-7 (variable across minerals)
Streak ColorLead-gray (Galena), Greenish-black (Pyrite), White (Calcite, Quartz)
CleavagePerfect cubic (Galena), Perfect rhombohedral (Calcite), None (Quartz), Indistinct (Pyrite)
FractureConchoidal (Quartz, Calcite, Pyrite), Subconchoidal/Uneven (Galena)
Specific Gravity2.65-7.6 (variable across minerals)
Colorsdark gray, silver-gray, brassy yellow, white, colorless
TransparencyOpaque (Galena, Pyrite), Transparent to Translucent (Calcite, Quartz)
Type LocalityLa Sirena Mine, Guanajuato, Mexico
Mineral GroupCarbonate (Calcite), Sulfide (Galena, Pyrite), Silicate (Quartz)
Usesore of lead, sulfur source, industrial abrasive, collector's specimen
Associated Mineralscalcite, galena, pyrite, quartz
Rarityuncommon
Description
A mineral specimen featuring dark gray, metallic galena crystals, brassy yellow pyrite specks, and white calcite crystals embedded in a matrix of granular, translucent quartz.
Geological Context
This assemblage is typical of hydrothermal vein deposits, often found in polymetallic ore bodies where lead, zinc, and silver minerals precipitate alongside quartz and carbonates from hot aqueous solutions.
