Difference between revisions of "Scapolite"
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Revision as of 09:25, 19 July 2008
|Chemical composition||Complex sodium aluminium silicate|
|Habit||Prismatic and massive|
|Cleavage||Distinct to perfect (depending on direction)|
|Optic nature||Uniaxial -|
|Refractive index||1.545-1.580 (depending on color)|
|Specific gravity||2.634-2.74 (depending on color)|
|Pleochroism||Medium to strong (depending on color)|
Scapolite can be easily confused with quartz - in particular the violet version with amethyst - due to overlapping refractive indices. The optic character for scapolite is uniaxial with a negative sign while quartz is uniaxial with a positive sign. In addition; quartz will usually show a bull's-eye. Separating the two is an generally an easy task (30 seconds) when one is familiar with the conoscope addition to the polariscope.
A fairly recent find (2005) in Badakhshan, Afghanistan is tenebrescent scapolite. This colorless to silvery material is unearthed near the hackmanite deposits and shows an aquamarine color after exposure to SWUV light. The intensity of this color (blue) depends on the time it has been exposed to the UV lightning. Exposure to an UVP UVG4 SWUV lamp for 15 minutes triggered an almost Santa Maria aquamarine blue color that faded gradually during the following 2-3 minutes in natural daylight.