Amethyst is the February Crystal for Aquarius and as such is considered to be a mind stone. Aquarius is an Air sign and deals which deals with matters of the mind. Amethyst's deep purple color is also associated with the Third Eye Chakra.
So when working with an Amethyst we see healing, most notably with mind chatter and anxiety. Also Because Amethyst is connected to the third eye charka it is an excellent crystal for opening your intuition and learning to trust your inner voice.