Tuesday, December 6, 2011

Gemstone Series --- Iceland Spar

History & Lore :
The name Calcite is a derivation of the Greek word for lime, “chalix”. The name “Iceland Spar” was brought about by the fact that this variety of Calcite was first discovered in Iceland.
Availability :
Calcite is one of the most commonly found minerals on earth, and is believed to be responsible for accounting for up to 4% of the weight of the earth's crust. Owing to the extremely wide distribution of Calcite deposits, and the wide range of situations in which it forms, Calcite is available in huge and diverse number of varieties.
Sources :
Calcite deposits are abundant, with instances occurring worldwide in locations including, Africa, Brazil, England (Cornwall, Durham, Lancashire), Germany, Iceland, India, Mexico, and many of the United States

Evaluation :
Iceland Spar (Calcite) is rated at 3 on the Moh's Scale of Hardness, and is a very soft gemstone. Because of it's softness Calcite is best used for earrings, pendants, brooches, or other applications where it will not be subjected to knocks / scratches.
Iceland Spar (Calcite) is found in colorless and white varieties and can exhibit wonderful transparency.
Calcite is usually transparent to opaque and some varieties exhibit fluorescence or phosphorescence, with specimens displaying beautiful bright colors when exposed to UV light. In fact, some examples continue to glow with color (phosphoresce), even after the UV source has been removed. In addition to this Calcite has a unique property, double refraction. What this means is that when rays of light enter the stone it is split, creating fast and slow beams of light. This causes the effect of anything and everything being viewed through Calcite appearing twice. This unique double refraction can also cause a rainbow effect in examples that have small crystal fractures.
The Iceland Spar variety of Calcite is the one that best exhibits the double refraction property.
erennially popular, and widely available, the extraordinary number of varieties and occurrences ensures that Calcite will likely always be a popular mineral. All Calcite examples are low to moderately priced and therefore available to all.

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