extrusive igneous rock, with poor cleavage, conchoidial fracture, with a hardness of roughly 5-5.5, and glassy

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extrusive igneous rock, with poor cleavage, conchoidial fracture, with a hardness of roughly 5-5.5, and glassy

2006-10-20 08:08:05 · 5 answers · asked by jeff j 1 in Science & Mathematics ➔ Earth Sciences & Geology

5 answers

Obsidian

2006-10-20 08:11:36 · answer #1 · answered by Anonymous · 0⤊ 0⤋

Volcanic osbidian. It's relatively soft with a hardness of 5 to 5.5.

The tendancy for conchoidal fractures made it a useful mineraloid for arrow and spear heads.

2006-10-20 15:16:40 · answer #2 · answered by Professor 3 · 1⤊ 0⤋

I would vote against obsidian as it is made up of non-crytsalline silica, so should present a hardness of at least 7. I'm not positive, but could you be describing a non-welded tuff?

2006-10-20 15:16:19 · answer #3 · answered by Anonymous · 0⤊ 1⤋

100% obsidian !!!

2006-10-20 16:13:00 · answer #4 · answered by Geo06 5 · 0⤊ 0⤋

could be porcellanite

2006-10-21 00:58:56 · answer #5 · answered by mandira_nk 4 · 0⤊ 0⤋