2.5" Hexagonal, Columnar Calcite and Fluorite - Fluorescent!

 
This is a beautiful association of hexagonal, columnar calcite crystals that formed in association with pristine, deep purple fluorite crystals. Small amounts of pyrite can be found peppered throughout the matrix of this specimen. Under short wave UV, the calcite crystals react by fluorescing a vibrant orange color.

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.

Fluorite is a halide mineral comprised of calcium and fluorine, CaF2. The word fluorite is from the Latin fluo-, which means to flow. In 1852 fluorite gave its name to the phenomenon known as fluorescence, or the property of fluorite to glow a different color depending upon the bandwidth of the ultraviolet light it is exposed to. Fluorite occurs commonly in cubic, octahedral and dodecahedral crystals in many different colors. These colors range from colorless and completely transparent to yellow, green, blue, purple, pink or black. Purples and greens tend to be the most common colors seen.

The mineral pyrite or iron pyrite is commonly referred to as Fool's Gold because its metallic luster and pale brass-yellow hue give it a superficial resemblance to gold. In the old mining days, pyrite was sometimes mistaken for gold. Pyrite is the most common of the sulfide minerals with the chemical formula FeS2. Pyrite crystals occur in many shapes and habits, including cubes of all sizes, penetration twin cubes, pyritohedral clusters and as small druzy crystals that can exhibit a beautiful glistening effect.
DETAILS
SPECIES
Calcite, Fluorite & Pyrite
LOCATION
China
SIZE
2.5 x 1.6"
CATEGORY
ITEM
#128558