Tennantite

Titanite, also known as Sphene (especially when cut for gemstones), is a rare mineral occasionally mined as a source of titanium dioxide, used to create white pigments. Exceptional, gem-quality crystals, which are usually somewhere on the green-yellow spectrum, are highly sought after by collectors. Cut titanite has extremely high dispersion, or "fire" (i.e., white light passing through it is dispersed into many colors - diamonds are also famous for having high dispersion).

Inesite is an appealing pinkish-brown translucent mineral that is sometimes confused with rhodonite. Its name comes from the Greek word for 'fiber' and refers to the sometimes fibrous appearance of this mineral. Inesite is uncommon to find in hydrothermal conditions often with manganese-rich metamorphic rocks. Its fracture is brittle and its streak is white.

Hornblendite is a rare igneous rock containing large amounts of hornblende, which is a combined group of dark-colored amphibole minerals. Hornblendite is often found alongside diorite, granite, gabbro, and peridotite. While uncommon, this rock is used for kitchen countertops, garden walkways and decoration, as well as entryway and flooring purposes.

Vauxite is a beautiful crystal occurring in light and dark transparent shades of blue. Vauxite crystals take on a flattened and parallel appearance, though the crystals vary in size. This secondary mineral can be found in apatite deposits in hydrothermal tin zones. Ferrivauxite is the oxidized result of vauxite.

Thaumasite is a rare mineral that occurs in the form of translucent or transparent hexagonal crystals. Although very attractive, thaumasite is quite soft and fragile, so you will usually find it cut into cabochons. Its name comes from the Greek word "thaumazein," meaning "to be surprised" or "to wonder," which refers to its unusual chemical compositions.

Clinochlore occurs in an attractive range of transparent and translucent dark greens. The fracture is uneven and the streak is white. No fluorescence is observed. Like other members of the Chlorite group, this mineral is pretty soft and has been used for carving and as decoration for hundreds of years.

Shigaite is a rare mineral currently known from just a few localities in the world. It comes in a form of small, hexagonal crystals with sharp edges. It carries the name after the Shiga prefecture in Japan, where it was discovered in 1985. Shigaite is often associated with other minerals and regularly sought by gemstone collectors.

The clarity and sheen of phosphophyllite make it an excellent selection for use as a gemstone; its brittle nature, however, makes it very difficult to sculpt into any usable form for jewelry. It is mostly used as a collectible gem in its raw state. It is rare to come across the largest specimens, which originate from Bolivia.