Obsidian is a crystal that I've always loved. It's birthed from volcanoes, literally coughed up by Mother Earth.
Black obsidian is a wonderful grounding stone associated with the root chakra and one that can transmute grief and trauma. How appropriate I am behind on my A to Z challenge, but because I took a few days off to care for my dying grandmother. If you were wondering, I have an obsidian heart with me.
Obsidian is also a wonderful stone of truth. It is highly protective as a shield against negativity and can help you release negative patterns and habits.
Snowflake obsidian is a variation and it literally looks like snowflakes on the black glossy stone. It is a stone of peace and healing. It can be used to clear energy blockages and keep focused during times of chaos and stress.
Obsidian can be found raw or tumbled. In Hawaii, there is a belief that you upset Pele, the Goddess of the Volcano, if you take anything from her. It's an interesting conundrum.
Rainbow obsidian is a black obsidian that when polished takes on a rainbow appearance of color. One of my favorite pocket stones is a small heart shaped rainbow obsidian. It is said to be a powerful meditative stone and one good for transmuting fears and releasing blockages and protecting you from depression. Some say it was a stone used by Nostradamus.
If any of this resonates with you, you might want to head to a metaphysical book store and check out their crystals and stones and pick up an obsidian.
Although I could do an entire A to Z on crystals alone (perhaps my next challenge?), this one will be brief. If you really want an in depth explanation of crystals and their spiritual properties, my favorite book is called Love is in the Earth.