Much precious opal occurs as thin seams and patches within a host rock of ironstone. Opal is a hydrated amorphous form of silica sio 2 nh 2 o. The stone above on the left is a boulder opal bead that displays tiny seams and patches of precious opal. The problem and opportunity. This stone is a naturally occurring matrix that embeds itself in large boulders of ironstone.
Boulder opal is unique in appearance because it is a mixture of opal and host rock generally iron stone. It is very difficult to give a simple description of the colors of boulder opals because every single one is different. Every color of the rainbow can appear in every possible combination and as we look into the gemstone the colors can change and move in a phenomenon called play of color. In some cases the opal is mixed in with the iron stone while other times the opal sits on top. About boulder opal about boulder opal.
Boulder opals have more variety and uniqueness compared to other opals and gemstones as so many factors have taking place over million years and different mineralization has helped in huge cross spectrum of unique boulder opals that you can enjoy. Its water content may range from 3 to 21 by weight but is usually between 6 and 10. Iron stone is the yellowish orange material you can see on each other stones. Because of its amorphous character it is classed as a mineraloid unlike crystalline forms of silica which are classed as minerals it is deposited at a relatively low temperature and may occur in the fissures of almost any kind of rock being. The stone on the right is a cabochon cut from rough found in the koroit opal field of queensland australia.
RELATED ARTICLE :
The stone on the right is a cabochon cut from rough found in the koroit opal field of queensland australia. Boulder opals have more variety and uniqueness compared to other opals and gemstones as so many factors have taking place over million years and different mineralization has helped in huge cross spectrum of unique boulder opals that you can enjoy. Boulder opal is unique in appearance because it is a mixture of opal and host rock generally iron stone. Much precious opal occurs as thin seams and patches within a host rock of ironstone.
