Strand of black satin agate to drop Ø 40x30 mm

TheAgate It is a variety of chalcedony, that is a cryptocristalline and microcrystalline quartz, usually with obvious colored color.

It's a gemstone that in nature exists in multiple colors, from white to black, crossing colors of yellow, red, orange, gray, pink, etc; Often enriched with special nuances. The colors are due to the presence of iron and manganese oxides.