4.4" Manganoan Calcite (Highly Fluorescent) With Pyrite - Peru

Manganoan calcite, also known as manganocalcite, is a pink, manganese-rich variety of calcite with a chemical composition of (Ca,Mn)CO3. It crystallizes in a trigonal crystal system and forms rhombohedral or scalenohedral crystals. These crystals tend to display a pink color that ranges anywhere from pinkish-salmon to hot pink. It often displays a bright orangey-pink fluorescence under short-wave UV light.

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.

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. Smaller (druzy) crystal aggregates may give off beautiful glistening effects, and larger crystals may be perfectly formed, including fascinating cubes, penetration twins, and other interesting crystal forms.