GUILTY PLEASURE
by The Fez 
, Thursday, February 11, 2016, 20:00 (3927 days ago) @ Johnny Briefcase
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.
Complete thread:
- GUILTY PLEASURE - Johnny Briefcase, 2016-02-09, 23:00
![[*]](themes/ZIP/images/complete_thread.png "Open whole thread")
- GUILTY PLEASURE - The Fez, 2016-02-10, 00:15
- GUILTY PLEASURE - Dooglas, 2016-02-11, 00:23
- GUILTY PLEASURE - Johnny Briefcase, 2016-02-11, 16:10
- GUILTY PLEASURE - HolyMole, 2016-02-11, 16:23
- Obsidian - islandgirl, 2016-02-11, 17:12
- GUILTY PLEASURE - The Fez, 2016-02-11, 20:00
- GUILTY PLEASURE - ZihuaRob, 2016-02-10, 08:45
- GUILTY PLEASURE - Pam & Denny, 2016-02-10, 09:11
- GUILTY PLEASURE - The Fez, 2016-02-10, 00:15
