Look up: mineraloid

1. 
   Mineraloid
   A `mineraloid` is a mineral-like substance that does not demonstrate crystallinity. Mineraloids possess chemical compositions that vary beyond the generally accepted ranges for specific minerals. For example, obsidian is an amorphous glass and not a crystal. Jet is a dense form of coal. Opal is another mineraloid because of its non-crystal nature. Pearls, considered by some to be a mineral because of the presence of calcium carbonate crystals wit...
   Found on http://en.wikipedia.org/wiki/Mineraloid
   
   
2. 
   mineraloid
   mineraloid 1. A naturally occurring, usually inorganic, mineral-like material that is amorphous and lacks a highly ordered atomic arrangement and characteristic external form; such as, opal or volcanic glass. 2. A metallic element in liquid form; such as, mercury at ordinary temperatures.
   Found on http://www.wordinfo.info/words/index/inf