Chocolate dogtooth calcite, large Wulfenite The near-black botryoidal mass is

The near-black botryoidal mass is an aggregate of spheres with radial structure inside

These pieces can be fascinating to study up-close

depositing a white crust of included quartz on the surface

Broken edges expose some layers to be composed of silvery needles radiating out

Note: I was able to remove the chip of matrix between the two larger formations (apparent in images 1 and 3) so it is less distracting from the aesthetics of the piece

Chocolate dogtooth calcite, large Wulfenite The near-black botryoidal mass isLocale: Santa Eulalia, Chihuahua, Mexico Approx size: 4 x 3 x 2. 5" Approx weight: 652g (about 1 1 3 lb) Known by the trade name "chocolate dogtooth calcite," this type of calcite from the famed Santa Eulalia mining district grows in hedgehog clusters of sharp dogtooth (scalenohedral) crystals. The variety gets its distinctive opaque brown appearance from iron oxides; a layer of hematite included calcite is deposited on the surface during a later