1) The top as well as the bottom “shutting points” of a crystal. See alsobasal pinacoid.
2) The mother or matrix rock that a crystal is resting on.
3) A chemical substance that is either a hydroxide, carbonate, or steel oxide that has the capacity to turn litmus paper azure, and has the capacity to respond with acids to form salts. Bases are alkaline and have a taste that is bitter.