Legrandite

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.

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.

Skutterudite is a grey, lustrous, and fairly rare mineral composed primarily of cobalt arsenide. The mineral’s unusual name is derived from a hill in southern Norway, where it was first discovered scientifically. Because it may contain high concentrations of iron or nickel, skutterudite is occasionally mined to be smelted for these elements. Particularly striking specimens are also sought after by rockhounds and collectors.

Commonly found across the globe, ilmenite has also been found in moon rocks! It is used for its titanium content, processed into ultra-strong metal alloys. It is also mined to create titanium dioxide, which is useful for coloration and polishing. When eroded by nature, it forms beautiful black sand beaches which indicate a prominent veins is close by.

Arsenic is an element regarded as a semi-metal or metalloid. It is regularly found in many different types of rocks and often bonds to sulfur. The most common mineral that contains arsenic is arsenopyrite, which also contains sulfur and iron. This element can be very harmful to humans by inactivating important enzymes related to DNA.