Look up: obsidian

1. 
   Obsidian
   a form of natural volcanic glass used to make projectile points and other tools
   Found on http://www.geocities.com/Athens/Acropoli
   
   
2. 
   Obsidian
   Obsidian is volcanic glass.
   Found on http://www.encyclo.co.uk/nol.php
   
   
3. 
   Obsidian
   A super-chilled igneous rock, black in colour and glassy in appearance. Fractures conchoidally. Often formed due to contact with cold seawater as the silicate minerals cool almost immediately, restricting mineral growth. Can also be called volcanic glass.
   Found on http://www.geologyrocks.co.uk/glossary/l
   
   
4. 
   obsidian
   [n] - acid or granitic glass
   Found on http://www.webdictionary.co.uk/definitio
   
   
5. 
   obsidian
   very viscous lava, rich in silica and lakales,..that..may solidify to bubble-free volcanic glass. Category: The cosmos • a dark, hard, glassy volcanic rock, usually having the same composition as volcanic granite. Category: Chemistry
   Found on http://www.mijnwoordenboek.nl/definition
   
   
6. 
   obsidian
   Natural glass produced by volcanic action. It is usually black or black-banded, and can be cut and polished and used as a gemstone.
   Found on http://www.antique-crafts.co.uk/glossary
   
   
7. 
   Obsidian
   Ob·sid'i·an noun [ Latin Obsidianus lapis , so named, according to Pliny, after one Obsidius , who discovered it in Ethiopia: confer French obsidiane , obsidienne . The later editions of Pliny read Obsianus lapis , and Obsius , instead of Obsidianus lapis , and Obsidius .] (Min.) A kind of glass produced by volcanoes. It is usually of ...
   Found on http://www.encyclo.co.uk/webster/O/5
   
   
8. 
   obsidian
   <chemical> A kind of glass produced by volcanoes. It is usually of a black colour, and opaque, except in thin splinters. ... In a thin section it often exhibits a fluidal structure, marked by the arrangement of microlites in the lines of the flow of the molten mass. ... Origin: L. Obsidianus lapis, so named, according to Pliny, after one Obsidi ...
   Found on http://www.mondofacto.com/facts/dictiona
   
   
9. 
   obsidian
   noun acid or granitic glass formed by the rapid cooling of lava without crystallization; usually dark, but transparent in thin pieces
   Found on http://wordnet.princeton.edu/perl/webwn?
   
   
10. 
    Obsidian
    `Obsidian` is a type of naturally-occurring glass formed as an extrusive igneous rock. It is produced when felsic lava extruded from a volcano cools rapidly through the glass transition temperature and freezes without sufficient time for crystal growth. Obsidian is commonly found within the margins of rhyolitic lava flows known as `obsidian flows`, where cooling of the lava is rapid. Because of the lack of crystal structure, obsidian blade edges ...
    Found on http://en.wikipedia.org/wiki/Obsidian
    
    
11. 
    Obsidian
    • (n.) A kind of glass produced by volcanoes. It is usually of a black color, and opaque, except in thin splinters.
    Found on http://thinkexist.com/dictionary/meaning
    
    
12. 
    obsidian
    natural glass of volcanic origin that is formed by the rapid cooling of viscous lava. Obsidian is extremely rich in silica (about 65 to 80 percent), ... [9 related articles]
    Found on http://www.britannica.com/eb/a-z/o/3
    
    
13. 
    Obsidian
    Glassy dark colored volcanic rock. Usually composed of rhyolite.
    Found on http://www.physicalgeography.net/physgeo
    
    
14. 
    Obsidian
    A volcanic glass that may be clear, black, brown or green in color, which is one of the finest raw materials for the chipping of stone tools.
    Found on http://members.aol.com/artgumbus/glossar
    
    
15. 
    obsidian
    Samples of obsidian. Credit: U.S. Geological Survey A dense volcanic glass, usually rhyolite in composition and typically black in color; there is a well known occurrence of it at Yellowstone Park, Wyoming. Compared with window glass, obsidian is rich in iron and magnesium; tiny (less than 0.0...
    Found on http://www.daviddarling.info/encyclopedi
    
    
16. 
    obsidian
    obsidian (obsid'ēun) , a volcanic glass, homogeneous in texture and having a low water content, with a vitreous luster and a conchoidal fracture. The color is commonly black, but may be some shade of red or brown, and cut sections sometimes appear to be green. Like other volcanic glasses, ...
    Found on http://www.infoplease.com/ce6/sci/A08363