6.8" Amethyst and Chabazite Crystals on Sparkling Chalcedony - India

This is a beautiful, 6.8" wide specimen that features an association of quart, amethyst, and chabazite crystals, all formed from a sparkling chalcedony encrusted matrix, collected from Madhya Pradesh, India. This formation occurred within a cavity/vug in the basalt host rock. Apophyllite, barite, and julgoldite crystals have also been reported as being present within some of these vugs.

The base of this specimen has been cut flat for presentation.

Amethyst is a purple variety of quartz (SiO2) that owes its violet color to natural gamma irradiation, iron impurities, and the presence of trace elements, which result in complex crystal lattice substitutions. It is 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, where they are found in hydrothermally-formed geodes, but many localities around the world produce an amazing variety of amethyst crystals and formations. They are almost always formed in medium- to high-temperature geological settings.

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.

Chavazite's general chemical formula is (Ca,K2,Na2)2[Al2Si4O12]2 · 12H2O.

Quartz var. Amethyst, Quartz var. Chalcedony & Chabazite
Khadakwani, Madhya Pradesh, India
6.8 x 2.6"