1.2" Amethyst and Chabazite Crystals in Basalt - India

Amethyst is a purple variety of quartz (SiO2) and owes its violet color to natural irradiation, iron impurities, and the presence of trace elements, which result in complex crystal lattice substitutions. It’s considered a semi-precious gemstone, and just two centuries ago was considered to have a value on par with diamonds, sapphires and rubies. The largest and best known amethyst deposits occur in southern Brazil and Uruguay but many localities around the world produce an amazing variety of amethyst crystals and formations.

Chabazite is the name for a series of minerals that include chabazite-Ca, chabazite-K, chabazite-Mg, chabazite-Na and chabazite-Sr. The variety of the crystal is dependent on the cation present during formation (Ca, K, Mg, Na or Sr). The red chabazite is commonly a calcium dominant variety (chabazite-ca), the most prevalent of the chabazite series. Crystals usually exhibit a rhombohedral habit and can display a variety of colors including red, orange, yellow and colorless.

The general chemical formula of chabazite is (Ca,K2,Na2)2[Al2Si4O12]2 · 12H2O .