3. The other black mineral is tourmaline. This one has a number of different faces but might look 3 or 6 sided. It may look like it's a part of a column. This specimen comes from Western Australia.

Tourmaline has the long chemical formula of Al₆B₃Fe₃H₁₀NaO₃₁Si₆

It is a mineral of many colors. It is most commonly black, but can be colorless, red, orange, yellow, green, blue, violet, pink, or other colors in between; can be bi-colored (two colored), or even tri-colored (three). Rarely it can be neon green or electric blue.

The mineral hardness scale runs from 0 to 10, and tourmaline has a hardness on the scale of 7 to 7.5.

If you rub a piece of tourmaline on a piece of white clay, you’d see that it leaves a white streak. DON’T do this without permission!

Tourmaline is most commonly found in granite, schist, and marble.

Tourmaline has been used by native Californians for centuries. San Diego County, California, is has been a producer of gem quality tourmaline for over a century.

The most gem quality tourmaline, though, is found Brazil and Africa.

Rocks that contain tourmaline include granite, sandstone, and shale.

 Geologic Map of Western Australia