Friday, December 27, 2013

Gemstone of the Week: Fire Obsidian

(Image of Fire Obsidian found on topgems.homestead.com
More images of Fire Obsidian





Fire Obsidian is very like the Rainbow Obsidian I blogged about last time. Just like Rainbow Obsidian, Fire Obsidian's interesting iridescence (or 'fire' as it is also called) is caused by the presence of Magnetite microcrystals. In Fire Obsidian, these microcrystals are in thin layers, which are roughly the thickness of the wavelength of light, whereas, in Rainbow Obsidian the layers of Magnetite microcrystals are in thicker volume and so gives the Obsidian larger bands of colour.  Fire Obsidian is only known to be found in Lake County, Oregon.