Monday, June 7, 2010

Iceland Spar

Gemstone :
Iceland Spar (Calcite)

Birthstone Month :
Iceland Spar (Calcite) is not associated with any particular birthstone month.

Zodiac :
Iceland Spar (Calcite) is not associated with any particular zodiac sign.

Chemical Symbol :
CaCO3

Chemical Make-up :
Calcite is a stable form of the mineral Calcium Carbonate, and is the primary mineral in limestone & marble.

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.

Common Cuts :
Calcite is most commonly fashioned into decorative ornaments and spheres, but mineral examples are also popular amongst collectors of Calcite, of which there are many. Gem quality Calcite can be cut into almost any known / recognized gemstone shape, although it is normally only faceted for collectors.

Iceland Spar (Calcite) is most commonly used in the manufacture of Nichol Prisms, which are an integral and essential part of optical instruments and polarizing microscopes.

Routine Enhancements :
There are no known enhancements for Iceland Spar (Calcite).

Care & Cleaning :
Calcite is best cleaned using a soft, dry cloth. Extreme heat and all acids should be avoided as Calcite is easily affected, even by relatively weak acids, which cause the stone to effervesce, or bubble. Calcite jewelry should be kept in a fabric-lined box, away from other harder jewelry that could easily scratch this soft mineral.

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