5.4" Calcite Crystals After Calcite on Druzy Quartz - Missouri

This specimen contains light-yellow calcite crystals that formed after deep yellow calcite. The matrix from which these calcite crystals formed is encrusted in a layer of druzy quartz. Under long wave UV, these calcite crystals exhibit orange fluorescence.

It comes with an acrylic display stand.

Calcite, CaCO3, is a carbonate mineral and the most stable polymorph of calcium carbonate. The other polymorphs are the minerals aragonite and vaterite. Calcite crystals are trigonal-rhombohedral, though actual calcite rhombohedra are rare as natural crystals. However, they show a remarkable variety of habits including acute to obtuse rhombohedra, tabular forms, and prisms. Calcite exhibits several twinning types adding to the variety of observed forms. It may occur as fibrous, granular, lamellar, or compact. Cleavage is usually in three directions parallel to the rhombohedron form.

Quartz is the name given to silicon dioxide (SiO2) and is the second most abundant mineral in the Earth's crust. Quartz crystals generally grow in silica-rich environments--usually igneous rocks or hydrothermal environments like geothermal waters--at temperatures between 100°C and 450°C, and usually under very high pressure. In either case, crystals will precipitate as temperatures cool, just as ice gradually forms when water freezes. Quartz veins are formed when open fissures are filled with hot water during the closing stages of mountain formation: these veins can be hundreds of millions of years old.
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DETAILS
SPECIES
Calcite & Quartz
LOCATION
Reynolds County, Missouri
SIZE
5.4 x 3.9"
CATEGORY
ITEM
#122123