The black silky stone is called Obsidian, the mineral is quite intriguing since it is formed in a special way. From deep down in the depts of the earth it emerges out of an active volcano, while it cools off with help from the cooler air on the surface of the earth, it hardens and becomes a magnificent black rock or some call it "volcanic glass".
Stone is a solid shield against negativity and a psychic smog harassing you, around you in your close environment.
This chakra stone is associated with the base chakra increasing self-control and support during a time of transition or change. A strength reminder of troubled times and protector of positivity in the most desperate times.