Base -	1) The top and the bottom "closing points" of a crystal. A base exists only in minerals that belong to the hexagonal, orthorhombic, tetragonal, and trigonal crystal systems. Also known as basal pinicoid.
	2) Matrix or foundation of a crystal.
	3) Chemical substance that is either a hydroxide, carbonate, or metal oxide that has the ability to turn litmus paper blue, and the ability to react with acids to form salts. Bases are alkaline and have a bitter taste.