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Encyclopedia > Nephrite
There is also a community named Actinolite,_Ontario in Canada.
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Well-cleaved, dark, fine-grained chlorite-actinolite metadiabase intrudes light granitic gneiss

Actinolite is an inosilicate mineral with the chemical formula
Ca2(MgFe)5Si8O22(OH)2

Contents
1 Mineralogy
2 Occurrence
3 Details
4 Related minerals
5 Reference

Mineralogy

Actinolite is an intermediate member in a series between tremolite (Mg-rich) and ferro-actinolite (Fe-rich). As seen from the chemical formula above, Mg and Fe ions can be freely exchanged in the crystal structure.


Occurrence

Actinolite is commonly found in metamorphic rocks, such as contact aureoles surrounding cooled intrusive igneous rocks. It is also occurs as a product of metamorphism of magnesium-rich limestones.


Some forms of asbestos are formed from fibrous actinolite, the fibres being so small that they can enter the lungs and damage the alveoli. Another form of actinolite, known as nephrite, is one of the two common constituents of jade (the other being jadeite).


Details

Crystallographic system Monoclinic
Colours Pale to dark green. White or grey when in asbestos form
Lustre Vitreous to dull glassy
Hardness 5.5-6
Refractive index 1.61
Cleavage 2
Pleochroism Yellow to dark green to transparent to opaque

Related minerals

  1. Tremolite
  2. Jade

Reference

  • Hurlbut, Cornelius S.; Klein, Cornelis, 1985, Manual of Mineralogy, 20th ed., John Wiley and Sons, New York ISBN 0471805807

  Results from FactBites:
 
Astrology & Gemstones, Birthstones: Nephrite Gem for Pisces - Gems shop online (220 words)
Nephrite, a silicate of calcium and magnesium of the amphibole group, is a mineral with a fibrous crystalline structure.
Nephrite is a white to dark green variety of jade, chiefly a metasilicate of iron, calcium, and magnesium.
Nephrite is composed of silica and magnesia and is dependent on its color by the amount of iron present in the mineral..
JADE, a gem variety of both Jadeite and Nephrite (304 words)
Nephrite is actually not a mineral, but a variety of the mineral actinolite.
The nephrite variety is composed of fibrous crystals inter-twinned in a tough compact mass.
Nephrite is usually only green and creamy white, while jadeite can have the full range of jade's colors.
  More results at FactBites »


 

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