Non-crystaline Minerals

Obsidian

Sometimes the magna expelled from a volcano cools so quickly that crystals are not able to form. If the magna is rich in silica it forms a type of glass called obsidian.

Chemically, obsidian is very similar to the igneous rocks, granite and rhyolite. If the magna cools slowly, deep within the Earth, it forms large crystals of granite. If it cools more quickly, near or on the Earth's surface, it forms smaller crystals of rhyolite.

 

Tektites

Tektites are lumps of glass, usually small, which are associated with meteorite impacts. They may be shaped like tears, rods, disks, buttons or dumb-bells. They may be black, brown or green.

Tektites may be either the remains of meteorites or they may be formed when meteorites hit the Earth. The collision causes molten rock to be ejected into the air. The molten rock cools quickly to form small glass beads.

Tektite

 


 

Non-crystaline specimens now available (at eBay):

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Mahogany Obsidian Polished Ball/Sphere 35mm Diameter, 55g

AU $18.33
End Date: Monday Jul-1-2019 0:30:49 EST
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1x Libyan Gold Tektite

AU $37.00
End Date: Friday Jul-12-2019 19:05:26 EST
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Darwin Glass (Darwinite) Tektite from Tasmania 6.58grams - Australian Seller

AU $16.00
End Date: Monday Jul-1-2019 15:00:56 EST
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2" Black Obsidian Round Scrying Mirror

AU $24.95
End Date: Saturday Jul-20-2019 13:54:48 EST
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One (1) Double Terminated Black Obsidian Point 181101-100mm Natural Crystal

AU $17.25
End Date: Saturday Jul-6-2019 7:34:31 EST
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Darwin Glass (Darwinite) Tektite from Tasmania 8.17grams - Australian Seller

AU $19.00
End Date: Friday Jul-5-2019 10:36:09 EST
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Darwin Glass (Darwinite) Tektite from Tasmania 6.98grams - Australian Seller

AU $16.50
End Date: Friday Jun-28-2019 13:52:35 EST
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