6" Calcite & Aragonite Stalactite Formation - Morocco
This formation of calcite coating aragonite comes from Ighoud, Morocco. This mass of mineral was removed from a cave where stalactite formations occur from iron-rich host rock and are enshrouded in layers of aragonite and calcite crystal.
Stalactites form when water that seeps through rock, reaches an opening such as a cave or tunnel. Once this mineral rich water (calcite in this case) precipitates out of the rock wall/ceiling, it leaves behind a crystal as the precipitate builds with each drop of water. Stalagmites are likely to form from this process, for the drops from the ceiling will still contain high mineral content, typically depositing a precipitate that will continue to build as long as water continues to flow in this location.
Aragonite is a carbonate mineral with the chemical composition of CaCO3. It is a pseudomorph after calcite and varies in colors depending on impurities. It displays a translucent to white color when pure, and when impure can vary between yellow, green, pink, blue and brown. Typically forming in low temperature hydrothermal veins, It is also known to form in hot springs, as precipitates from chemicals in sedimentary rock, and in some cases as crystals in fossilized sea creatures.