Amethyst and Citrine Cathedrals

Amethyst and Citrine Cathedrals Rock Professor Image

The cathedrals are true wonders of nature - they come from a series of basaltic flows in the southern Brazilian state of Rio Grande do Sul. They are mined by hard rock mining methods, then cleaned cut and polished by local craftsmen.

Cathedrals are large GEODES  formed in large gas bubbles in basaltic lava.

Cathedrals are graded for sale by exterior size and shape; crystal size, color and perfection; and overall appearance. Also, the appearance of other minerals such as calcite and quartz which form after the amethyst, may add to the value.

Go to these Rock Professor pages for more information on AMETHYST or CITRINE.

Amethyst: Chemistry: SiO2 ♦ Variety: Quartz ♦ Transparency: Transparent to translucent ♦ Luster: vitreous ♦ Crystal system: Trigonal ♦ Moh's hardness: 7 ♦ Color: Various shades of purple ♦ Localities: Southern Brazil and Uruguay. Citrine: A yellowish-brown variety of quartz often formed by heating amethyst