Mineral description : Vermiculite

Vermiculite from Malmberget.

Vermiculite with stellerite balls from Malmberget.

Vermiculite, heated at one side, from Malmberget.

Mineral class	Silicates : Phyllosilicates : Mica group
Chemical formula	(Mg,Fe,Al)3(Al,Si)4O10(OH)2.4H2O
Crystal system	Monoclinic
Habitus	Lamellar.
Cleavage	[001] perfect.
Hardness	1.5-2
Density	2.3 - 2.7
Color	Colorless, green, greenish black, yellowish brown.
Streak	Greenish white.
Luster	Vitreous.
Description	Vermiculite is an industrial mineral and have been used for over 80 years. Mainly in construction, agricultural, horticultural and industrial areas. It is mined at many localities around the world.
Occurance
Associates
Notes	The homepage of The Vermiculite Association Vermiculite exfoliates ( expands ) when heated. The increase in volume is about 10 times, sometimes up to 30 times. The exfoliation comes from the release of steam between the mica layers. When the water is released the color changes too.
Locations	Swedish localities : Malmberget, Lappland. As dark greenish black mica aggregates. Junosuando, Pajala, Norrbotten. Muruhatten, Strömsund, Jämtland. Handöl, Åre, Jämtland. Nordmark, Värmland. Harstigen, Värmland.

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