Bixbite

Bixbite (also known as red beryl, red emerald, or scarlet emerald) is a red variety of beryl, Be₃(Al,Mn)₂Si₆O₁₈. It is very rare, only known to occur in a few locations in the western United States and one in Mexico. Bixbite was named after Maynard Bixby.

Bixbite occurs in topaz-bearing rhyolites. It formed by crystallizing under low pressure and high temperature from a pneumatolitic phase along fractures or within miarolitic cavities and rhyolitic magmas near the surface. Minerals it is found with include bixbyite , quartz, orthoclase, topaz, spessartine garnet, pseudobrookite and hematite. The red color is thought to be from manganese substituting for aluminium in the beryl structure.

Gem-quality bixbite is very rare, and the largest faceted gemstones are less than three carats in size.