Obsidian

Obsidian

          The large area of distribution obsidian of fine jewelry qualities is in Armenia (neogenic volcanic domes of Arteni, Gumush-Garaber, Gyadis); Georgia (Paramskoe), Azerbaijan (Kacheldagskoe). Azerbaijan deposit is characterized by lava streams sour effusives - rhyolites, extent in 1-7 km, capacity more than 100 meters. Streams of lava are non-uniform: they are combined by glassy versions, the upper versions are deposited as thin striped, passing in glassy differences and obsidian. Sometimes the top part of a stream is submitted by clumpy lavas, either perlites or irisation silvery obsidian.
     Color of obsidian is from light gray, brown, reddish up to pitch-black. There are striped, like-breccias versions, with rare irisation of green and red color. Some versions of obsidian are similar to smoky quartz and morion. There are known the deposits of obsidian of red and brown color in East Kazakhstan, in Semeytukskiy magmatic complex of the Perm age, and also other areas which studied insufficiently.
     The structure of obsidian is - sour volcanic glass, contains up to 75 % silicate; is fragile; is rather easily processed and well polished.
     Hardness: 5 - 6 on Mohs scale.
     Break: like-shell, some versions are transparent in thin breaks.
     Shine: glass.
     Coloring and figure of obsidian gives inclusions of oxides of iron, field spate, amphibole, and silver-perl or golden irisation - give inclusion of microscopic gas.
     Obsidian it is applied to produce the various hand-made wares, souvenirs, and also inserts in jewels.
     Georgia, Armenia, Azerbaijan - the basic areas of extraction of obsidian by opencast way.