GUILTY PLEASURE

... on the hunt for quartz obsidian glass.

You may be on the hunt for a while longer, as there is no such thing as obsidian quartz.

Sorry, as a former geologist, I couldn't resist the temptation.

All the locals call it quartz. What is it then ? - just glass ?

......JB CEO of SFA

The locals call the stuff that comes out of your taps "agua potable", but only the foolhardy, or the very poor, would risk drinking it.

Obsidian is volcanic glass: Lava that has cooled very quickly, minimizing crystal formation. Quartz is all crystals.
Each volcano has a distinct composition of lava, and therefore obsidian. When we find obsidian artifacts in archaeological sites here on Vancouver Island, we know it didn't come from here as 'we got no volcanoes'. We can send the piece to a lab and have it tested, then trace it to it's home volcano. Helps us to figure out ancient trade routes, etc. Obsidian was highly prized as it produced extremely sharp cutting tools.

All the locals call it quartz. What is it then ? - just glass ?

......JB CEO of SFA

Obsidian is quickly cooled lava which forms a black, glass like rock. Very useful for early peoples as it breaks conchoidally into nice sharp edges, suitable for cutting implements. Obsidian is silicon dioxide (SiO2), for the most part. Because it lacks crystalline structure, it cannot be technically classified as a mineral, which means nothing to anyone not interested in trivial details.

Quartz is an extremely hard mineral (harder than steel) made of SiO4, with a distinctive hexagonal crystal structure. Add a few key elements, and you have a nice gemstone, like amethyst. Quartz is used to make glass and is one of the most common minerals found in rocks, especially granite.