Mineral description : Actinolite

Actinolite crystals in talc from Altemark talc mine, Norway.
Dark green actinolite crystals in talc and magnesite Altemark talc mine, Norway.

Mineral class Silicates : Inosilicates : Tremolite - Glaucophane - Riebeckite group.
Chemical formula Ca2(Mg,Fe)5(OH,F,Si4O11)2
Crystal system Monoclinic.
Habitus Thin long prismatic crystals. Also common as needle thin aggregates and fibrous aggregates (asbesthos)
Cleavage Perfect in two directions with 124 degrees angle.
Hardness 5-6
Density 3.1-3.3
Color Dark green, darker than tremollite.
Streak  
Luster  
Description  
Occurance In hydrothermally metamorphed magmatic rocks. In metamorph scarns.
Associates  
Notes  
Locations A very common mineral in many Swedish mines.
  • Kallmoraberg, Norberg, Västmanland. As nice dark green crystals.
  • Riddarhyttan, Västmanland.
  • Falu copper mine, Falun, Dalarna.
  • Altemark, Mo i Rana, Norway. As dark green crystals in talc.

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Last changed : 1998-12-29