This is a natural stone mined in Brazil with black /brown spots in it.These are believed to have been caused by natural radiation in the earth ions ago.Interesting collectors item.

Weight 9.85 cts app

Size 20 x 13 x 6 mm app

Quartz is the most common mineral on Earth. It is found in nearly every geological environment and is a component of almost every rock type.  It makes up about 12% of the earth's crust, occurring in a wide variety of igneous, metamorphic and sedimentary rocks. It is also the most varied in terms of variety and color.  Quartz is a 7 on the Mohs scale of hardness..