Chocolate dogtooth calcite, large Picture jasper Chalcedony is the cryptocrystalline version

Chalcedony is the cryptocrystalline version of quartz with similar requirements for growth

and a bit of clarity despite the white inclusions responsible for the crazed (crackled) pattern that radiates out from the center of each face

with some showing a lighter golden brown coloration

with selenite and light-to-orange-yellow siderite on a heavy base composed of several minerals

Wulfenite from the Glove Mine commonly is also commonly a dark brown-black

Chocolate dogtooth calcite, large Picture jasper Chalcedony is the cryptocrystalline versionLocale: Santa Eulalia, Chihuahua, Mexico Approx size: 5. 5 x 3. 5 x 1. 75" Approx weight: 542g (a bit over 1 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