aragonite - "cave calcite" - El Potosi Mine, Santa Eulalia Mining District, Chihuahua - hand/display specimen leading to the formation of

leading to the formation of lens-shaped orebodies of magnesite

The rhombohedral cleavage is less important than the effervescence in dilute hydrochloric acid

the greenish sand is composed of grains of olivine that weather out of the basalt of an old cinder cone

forming a layer cake of silty sediment and peat

When it is placed above a line drawn on paper and rotated

aragonite - "cave calcite" - El Potosi Mine, Santa Eulalia Mining District, Chihuahua - hand/display specimen leading to the formation ofaragonite CaCo3 Aragonite is a pseudomorph of calcite, with the same chemical formula, calcium carbonate, but a different crystal structure. When carbonated groundwater contains calcium, it most commonly precipitates calcite when cold and aragonite, when hot. Sometimes called "cave calcite," this aragonite comes from the Potosi Mine in the Santa Eulalia Mining District, Chihuahua, Mexico. The silver, lead, zinc and copper ores in this mine are