OPTICAL CALCITE TWIN CRYSTALS

OPTICAL CALCITE TWIN CRYSTALS

A striking specimen of Optical Calcite Twin Crystals.   Optical Calcite like this specimen show the classic double refraction.  This is where if you put the Calcite on some printed words, you will see a double reflected image of the words.  This is also a twin, a rarer form of calcite from a very cool stuff.  A great addition for your calcite or mineral collection.  This form of Calcite is called Iceland Spar.

Location:
Mariental District, Hardap Region, Namibia.

Dimensions:
6.2cm x 3.4cm x 6cm, 132g.

CaCO3, Calcium Carbonate.

Calcite, which gets its name from “chalix” the Greek word for lime, is a most amazing and yet, most common mineral.  It is one of the most common minerals on the face of the Earth, comprising about 4% by weight of the Earth’s crust and is formed in many different geological environments.  Calcite can form rocks of considerable mass and constitutes a significant part of all three major rock classification types.  It forms oolitic, fossiliferous and massive limestones in sedimentary environments and even serves as the cements for many sandstones and shales.  Interestingly Limestone becomes marble from the heat and pressure of metamorphic events.  The crystals of calcite can form many different shapes.  The positive rhombohedron, negative rhombohedron, steeply, moderately and slightly inclined rhombohedrons, various scalahedrons, prism and pinacoid.