Opal (Var: Precious Opal)
Coocoran Opal Fields, Lightning Ridge, Finch Co., New South Wales, Australia
About 60mm across. Mined 1-10-2012 from about 20 metres underground. Specimens such as this one, where opal fills cracks within silicified claystone, are called "angelstone" by opal miners within the Lightning Ridge region. Light coloured flecks within the silicified claystone are plant fossil fragments.
© M Goodwin 2012