3.4" Sparkly, Lavender Amethyst Geode Half - Argentina

The material has been analyzed at the California Institute of Technology and was described as "purplish pink amethystine quartz additionally coloured by microscopic hematite particles". They are not rose quartz or pink quartz as classically defined".

So, it's formed by the same processes that give amethyst its purple color, but by definition amethyst is purple not pink. So, we are left with a conundrum of what to call it, but since the majority of people seem to be calling it "pink amethyst" we will stick with that label.

Silicon Dioxide, also known as SiO2 or Quartz, is the second most abundant mineral in the Earth's crust. Quartz crystals generally grow in silica-rich, hot watery solutions called hydrothermal environments, at temperatures between 100°C and 450°C, and usually under very high pressure. Quartz veins are formed when open fissures are filled with hot water during the closing stages of mountains forming, and can be hundreds of millions of years old.

Calcite, CaCO3, is a carbonate mineral and the most stable polymorph of calcium carbonate. The other polymorphs are the minerals aragonite and vaterite. Calcite crystals are trigonal-rhombohedral, though actual calcite rhombohedra are rare as natural crystals. However, they show a remarkable variety of habits including acute to obtuse rhombohedra, tabular forms, and prisms. Calcite exhibits several twinning types adding to the variety of observed forms. It may occur as fibrous, granular, lamellar, or compact. Cleavage is usually in three directions parallel to the rhombohedron form.