This Obsidian pendant is about 3 inches long .
Necklace is 24 inches 
Obsidian is considered the stone of the Mayan and Aztecs. The volcanic rock was so abondant in the region that they used it for pretty much everything from utensils, to jewellery to weapons and therefore never really developed metallurgy.In that region Obsidian had more value than Gold.
The Mayan prophets and high priest used polished Obsidian as “mirrors” for scrying purposes; their way of prophesizing the future. 
A strongly protective stone, Obsidian forms a shield against negativity, providing a grounding cord from the base chakra to the center of the earth.  It absorbs negative energy from the environments and blocks psychic attack and negative spiritual influences. Obsidian brings clarity to the mind and clears confusion. Providing deep soul healing, Obsidian goes back to past lives to heal festering emotions or trauma carried forward into the present, bringing depth and clarity to emotions.
In ancient Mexican culture, Obsidian was called Itzli, which literally means the God Stone.