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Obsidian Pictures

 

OBSIDIAN

IGNEOUS ROCK CLASSIFICATION - Where does OBSIDIAN fall in the classification of igneous rocks?

APACHE TEAR big.jpg (386679 bytes) TEAR IN PERLITE big.jpg (388424 bytes)

The above obsidian specimen is an "Apache Tear".  It is a nodule of obsidian that has persisted through the devitrification process of a larger mass of obsidian.  The picture on the right is an Apache tear nodule in perlite.  The perlite is result of the devitrification process.

GRAY OBSID big.jpg (446557 bytes) A sample of gray obsidian from near Mono Lake, California.

 

banded obsidian big.jpg (408658 bytes) This is a very thin slice of obsidian that shows dark flow bands.

Obsidian also has a use as a surgical scalpel.   Because the obsidian is a glass (amorphous - without any internal structure), it can be honed to an extremely sharp edge.  Steel scalpels can be very sharp but are limited to the structure of the crystal boundaries.  In glass, there is no such boundary and the cutting surface can be much finer.

This scalpel has been shaped and is ready for the final polishing stage.  The left side of the knife is the cutting edge.