Hickoryite can only be found in Durango, Mexico. Hickoryite, also known as Autumn Hickoryite, is a trade name for a specific variety of brown rhyolite.
Rhyolite is a rock made up of quartz, feldspar, mica, and hornblende, and is very closely related to granite. While granite forms below the surface of the earth, rhyolite is an igneous rock that forms when magma is expelled from below the surface as lava and then cools rapidly.
Rhyolites, including Hickoryite, are said to bring calm to its wearers.