This is a lovely moon shaped Tibetan Tektite, highly polished.
Tektites are gravel-sized bodies composed of black, green, brown, or gray natural glass formed from terrestrial debris ejected during meteorite impacts. The term was coined by Austrian geologist Franz Eduard Suess, son of Eduard Suess. They generally range in size from millimeters to centimeters.
The last two pictures show the colouring of the tektite with a light source, although this moon is spherical and dense so very hard to see.
This tektite weighs 45g and measures 38 x 32 x 27mm
Thank you for looking
Castle Rocks Cornwall x