This is a partially polished rhodochrosite stalactite segment, collected from the Capillitas Mine in Argentina. The banding of this specimen is beautifully defined and contains wonderful coloring. The center of the specimen contains masses of pyrite with fantastic metallic luster. The portion of this mine that produced these types of banded rhodochrosite specimens, was mined out decades ago.
Rhodochrosite is a manganese carbonate mineral with them chemical composition MnCO3. The crystals typically have a pink-red coloration and cleaves with rhombohedral cleaving in three directions. It forms from hydrothermal pockets and can be found as both crystals and in banded formations.
The mineral pyrite or iron pyrite is commonly referred to as Fool's Gold because its metallic luster and pale brass-yellow hue give it a superficial resemblance to gold. In the old mining days, pyrite was sometimes mistaken for gold. Pyrite is the most common of the sulfide minerals with the chemical formula FeS2. Pyrite crystals occur in many shapes and habits, including cubes of all sizes, penetration twin cubes, pyritohedral clusters and as small druzy crystals that can exhibit a beautiful glistening effect.