What type of rock is Chrysacolla?

Answer 1

Chrysacolla (Cu3Al)2H2Si2O5(OH)4.nH2O is a ornamental gemstone with a hardness of 2.0 to 2.6 when dull, and near 7.0 when silica is present. Its not a true rock but a mixture of minerals of copper like malachite, some quartz, some turquoise and bits of brown matrix. When mixed with Malachite (Copper Carbonite) it was known as Eilat stone in the Gulf of Aqaba at Eilat. It is a often seen as light blue, blue to greenish blue. With silica (Quartz) when polished it tend to feel slightly greasy and has a vitreous luster. There is no cleavage but it does display a conchoidal fracture when chipped or broken. Its name comes from the Greek words meaning "Gold" and "Glue" It was a name of a material used in soldering gold. The nameis often applied now to borax, which is so employed. It is often found in the upper veins (oxidized zones) of copper mines. Today it is used for paper weights, ring stones and ornamental spheres. When found blue and covered with thin crystals of quartz it is much in demand as a decorative mineral specimen.