All of our Rocks are 100% Genuine Specimens & come with a Certificate of Authenticity

Specimen: Obsidian

Type: Igneous Rock

Location: Mexico

Scale cube=1cm: Full sizing please see photo

Obsidian is a naturally occurring volcanic glass formed as an extrusive igneous rock.

It is produced when felsic lava extruded from a volcano cools rapidly with minimal crystal growth. Obsidian is commonly found within the margins of rhyolitic lava flows known as obsidian flows, where the chemical composition (high silica content) induces a high viscosity and polymerization degree of the lava. The inhibition of atomic diffusion through this highly viscous and polymerized lava explains the lack of crystal growth. Obsidian is hard and brittle; it therefore fractures with very sharp edges, which were used in the past in cutting and piercing tools, and it has been used experimentally as surgical scalpel blades.

Igneous rocks are formed either deep underground within the earth, when magma becomes trapped in small pockets and slowly cools down to a solid form, Or above ground after volcano eruptions when lava cools down and becomes a solid form. Common types include Granite, Basalt, Gabbro, Pumice and Rhyolite.

The image shows the ACTUAL specimen you will receive.