Large hollow chalcedony nodule

Locale: Morocco

Approx size: 2 x 2 x 2"

Approx weight: 232g

Sometimes called “truffle,” “womb stone,” or “witches wart” chalcedony (hey, you don’t even want to know what I was calling them), these nodules have slightly obscene-looking bulbous, knobby forms in contrasting white and dark brown-gray semi-translucent chalcedony. The nodules are actually believed to be a fossil pseudomorph of prehistoric sponge colonies dating back to the Upper Cretaceous period. These minerals have only been found in Western Sahara, Morocco.

Chalcedony is the cryptocrystalline version of quartz; it has the same chemical composition (silica) but different crystal structure (cryptocrystalline vs. crystalline). Some of the nodules are hollow and crystal-lined inside similar to a geode, and can make for interesting pieces to cut open.

I call this one the "big boi." When I cleaned the specimen, the hole in the front was packed with dirt. I soaked it and picked away at the dirt with a toothpick, and the dirt just kept coming out. Turns out it's hollow like a geode and the holes on the front and back connect.

UV reactivity will glow orange under 365nm UV light, with brief phosphoresce (try it in the dark, with a strong UV light!).