“Bringing The Past, Into the Future”

Northern Geological Supplies Ltd
Northern Geological Supplies Ltd

“Bringing The Past, Into the Future”


£5.31£88.50 ex VAT



Obsidian is a naturally occurring volcanic glass derived from a rapidly cooled high silica lava. Often associated with the margins of Rhyolitic lava flows. It has little or no discernable crystalline structure. Specimens are supplied in a polythene bag in lots of 1 kg with a label.

SKU: obs1kg Category:

Obsidian is a natural volcanic glass. An extrusive igneous rock. It is produced when silica rich lava extruded from a volcano rapidly cools minimising crystal growth. Obsidian is commonly found within the margins of rhyolitic lava flows known as obsidian flows. The high silica content (70 -75%) produces a highly viscous lava with some degree of polymerization. The inhibition of atomic diffusion through this highly viscous and polymerized lava explains the lack of crystal growth. It is classed as metastable as over time it will crystalise. Non has been found over Cretaceous in age. Obsidian is hard and brittle with a concoidal fracture it therefore breaks with very sharp edges, which were used in the past in cutting and piercing tools. It has been used experimentally as scalpel blades.

Additional information

Weight 100 g

1 kg, 5 kg, 10kg, 25 kg


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