Garnets

People love garnets because of their colors and shape. The most common color is deep red, but they also come in black, green, cream, and other colors. Perfect garnet crystals have 12 diamond-shaped sides. Clear (but colored) garnets are used in jewelry, but garnets more commonly contain tiny inclusions that make them opaque and 'dirty' looking. The unusual hardness of garnets (H ~ 7) makes non-jewelry garnets great in sandpaper.
The largest garnet here is over an inch across. The cream-colored garnet has a perfect crystal form. The bottom and right garnets also show the diamond-shaped faces, while the top garnet is just irregularly round.

The 'dirty' garnet on the right has many inclusions.
These deep red garnets are roughly the size of BBs. Their shapes are round but irregular.

This photo looks good blown up. Click on the photo for a full-sized image.
These garnets are roughly the size of the tiny pellets used in bird shot (< 1 mm).

If you zoom in on these, you will see that many show the diamond faces of the perfect 12-sided garnet.

By the way, a 12-sided figure is called a dodecahedron.
This close up of garnets roughly 5 mm across shows that garnets have no cleavages, just irregular fractures.

The greenish streaks running up and down from each garnet are chlorite pressure shadows that formed when the rock was being stretched. This took place some 15 million years ago in the Snake Range of eastern Nevada.
This is an example of well-formed garnet crystals in a rock. If you zoom in on the picture, you can see the 12-sided crystal faces.

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