Chrysocolla in Cuprite

This stone is really two stones that grew together. The blue-green parts are chrysocolla, and the red-brown parts are cuprite. Both minerals contain copper, and both form in the same place: the zone where copper deposits meet oxygen and water and start to change.

Chrysocolla is fairly soft, 2.5 to 3.5 on the Mohs scale, and on its own it is too fragile for jewelry. When silica soaks into it, it hardens a lot, reaching up to 7 in that form. Cuprite is a simple copper oxide, and almost 90 percent of its weight is copper. Next time someone tells you a stone is worthless, remind them it is practically a coin.

The name chrysocolla comes from Greek: chrysos, gold, and kolla, glue. Theophrastus used it as early as 315 BC, because it was the name of a material used to solder gold. Cuprite comes from the Latin cuprum, copper. It is sometimes called "ruby copper" because of its color.

Material with this combination is sold as Sonora Sunset. According to the stone dealer Barlow's Gems, it came from the Milpillas mine in Sonora, Mexico. The deposit was discovered in 1978, mining began in 2006, and the mine closed in 2019, so this material is getting harder to find.

Israel has chrysocolla too: according to Hebrew Wikipedia, it is found in the Timna Valley. It is also one of the minerals that make up Eilat stone, which is considered the national stone of Israel.