Calcite is composed of the same material as limestone: calcium carbonate. This transparent crystal can be found in a variety of colours, such as blue, when it is charged with impurities. As a healing stone, blue calcite is especially calming and promotes calm communication. It is often used to help one become aware of their need for sleep. For students it is helpful for retaining new information. This clarity of mind that comes from blue calcite is helpful in all forms of communication and thought, most especially in difficult discussions. It can aid one to speak calmly and with tact.