Black obsidian stone, for use in jewelry. What is ?: obsidian
black rock is a volcanic glass sometimes called, is a volcanic
igneous rock belonging to the group of silicates, with a chemical
composition of aluminum silicates and a large percentage (*0% or
higher) slicos oxides. Its composition is similar to granite and
rhyolite.
Obsidian is not a mineral, because it has a well defined chemical
composition. Often it is classified as a Mineraloid. Hardness on
the Mohs scale is 5 to 5.5. Its specific gravity is 2.6. The
conchoidal fracture surface is, ie curve.
Its color is black, but may vary according to the composition of
impurities from very dark to light green, reddish and be veined
white, black and red. The iron and magnesium the color from dark
green to dark brown. It has the quality to change its color
depending on how cut. If you cut parallel its color is black, but
cut perpendicularly color is gray.
We have SGS, brown colors black rock. Delivery as requested by
buyer......
