3.9" Green, Hedenbergite Included Quartz with Calcite - Mongolia

This specimen includes green quartz crystals that formed in association with sheets of hedenbergite included calcite, collected from the Huanggang Mines of Inner Mongolia. The green color of the quartz can be attributed to hedenbergite inclusions as well. These needle-like inclusions become apparent when looking at the crystal's termination and/or backlighting the crystals. The quartz crystals at the center of the calcite feature an unusual quartz formation known as "interrupted quartz". The formation of the quartz was hindered by the calcite, resulting in oddly shaped quartz crystals.

It comes with an acrylic display stand.

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.

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.
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DETAILS
SPECIES
Quartz var. Prase (Hedenbergite inclusions) & Calcite
LOCATION
Huanggang Mines, Chifeng, Inner Mongolia
SIZE
3.9 x 3.2"
CATEGORY
ITEM
#163992