Ilvaite

Anglesite is a lead-containing mineral that forms crystals of varying colors. Occasionally mined for its lead content (lead has tons of commercial and industrial uses), high-quality specimens are also sought after by collectors. Crystals occasionally exhibit exquisite colorations, with blue, green, orange, violet, and yellow-hued varieties being particularly prized. Though found in multiple locations across the world, many collector-quality anglesites come from Morocco.

Greenstone is a field term used to describe any dense, dark-green altered or metamorphosed basic igneous rock. The distinctive green color of greenstone is typically caused by the presence of epidote, actinolite, or chlorite.

Hornblende is a term commonly used to describe dark green to black amphiboles. While it is not officially recognized as a distinct mineral, the name is widely used in the field to refer to this particular group of minerals. Hornblende minerals are often found in igneous and metamorphic rocks. Hornblende is often associated with other minerals like feldspar and quartz. Its presence in rocks provides valuable clues about their geological origins and history.

Legrandite is an extremely rare mineral prized by collectors for its yellow or yellow-orange color. Although exceptionally beautiful, this mineral doesn't find its use in jewelry because of its fragility. The smaller specimens are transparent, but the bigger the crystal the more opaque it gets.

Being a very rare, crystalline mineral, bixbyite is highly sought by mineral collectors. It is particularly prized when in the so-called "matrix" form - a matrix is a fine groundmass that has embedded crystals or larger grains emerging from it. Bixbyite is a manganese iron oxide, but the content of iron can vary significantly across samples. It is mined in the Kalahari Desert, South Africa.

Connellite is a rare mineral occurring in transparent blue. These minerals can be found in spiky formations with delicate spines and fibers. Connellite is named after chemistry professor, Arthur Connell, from Edinburgh, Scotland. This mineral has since been discovered in a couple of hundred locations over several continents, though in low concentrations.

Pezzottaite is a newer addition to the mineral world and was only discovered deep within Madagascar in 2002. After its first discovery, it was mined extensively and thought to be thoroughly mined out. It wasn't until recently a new cache of this remarkable gem was found in Afghanistan.

Analcime is a unique mineral that can actually cause itself to crystallize without outside interference. It was named in 1901 after the Greek term for "not strong," which is in reference to its inability to produce electricity when heated. Its crystals are not very hard, which is not surprising given that they are made predominately of sodium and aluminum.