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Actinolite

There is also a community named Actinolite,_Ontario in Canada.

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

Contents

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 systemMonoclinic
ColoursPale to dark green. White or grey when in asbestos form
LustreVitreous to dull glassy
Hardness5.5-6
Refractive index 1.61
Cleavage2
PleochroismYellow 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
Last updated: 10-26-2005 05:07:03
Last updated: 01-04-2007 01:18:57
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