This is an brilliant slab of chrysocolla and malachite from the Bagdad Copper Mine in Arizona. It is a wonderful association of blue chrysocolla with forest green malachite. Comes with an acrylic display stand.
Please note: This slab has not been polished, rather it has been coated in a clear epoxy that gives it a glossy, polished look. This method is substantially less costly than polishing the slabs, so they can be sold at a substantially lower price.
Chrysocolla is a basic copper silicate that typically forms as a pseudomorph following other copper based minerals. The chemical formula is considered undetermined due to the varying substitutions of elements and water content in its chemical structure. However, there is a form of chrysocolla with an identifiable chemical formula of Cu2H2Si2O5(OH)4, that can be found in microcrystals.
Regularly, chrysocolla will form as botryoidal lumps and spheres, rarely forming visible crystals. It's also been known to form in both solid and fibrous veins, over fibrous minerals and in crusts. Known for its sharp and vibrant coloring, chrysocolla can display a wide variety of colors such as blueish-green, bright green, light blue to even sometimes multicolored specimens, depending on the atmosphere present during formation.
Malachite is an intense green copper-based mineral that can be found in a wide variety of forms. Malachite
can grow in botryoidal masses, stalactitic formations, and reniform formations, typically as a tight cluster of fanning fibrous needles that make up a seemingly solid mass. As layers continue to stack during formation, a banded pattern can sometimes begin to take shape, which explains the rings in all shades of green that are seen on most polished malachite specimens.
Malachite results from the weathering of other copper ores and is very often found associated with other copper-based minerals such as Azurite and Chrysocolla. It can be found in copper deposits around the world, but the Democratic Republic Of The Congo is the primary source for polished malachite and mineral specimens.
Malachite has been prized since ancient times, first as a utilitarian copper ore, then as an ornamental stone. Due to it's value as a decorative stone, it's rarely mined as a copper ore anymore.