Obsidian is the stone of mastery over the physical plane. It has very powerful Scorpio-Capricorn vibrations. It is also called the Stone of Saturn. A jewel-like product of nature, it is probably a fossil bean. In size and appearance, it resembles the eye of an ox, whence its name.
Olivine frees the mind from sadness and evil passions.
The Onyx is a veined gem with chalcedony in parallel layers of different shades. It is used for making cameos, the figure being cut in one layer with the next as the background. Also pure black. Mohs 6.5 - 7. Onyx cools love's ardors, and it provokes discord.