A rare, green-colored form of this mineral used in jewelry is called prasiolite. This mineral can possess planar deformation features, and one variety of this mineral is called chalcedony. It is at the bottom of Bowen's Reaction Series, and this mineral exhibits piezoelectricity, making it useful in watches and radio transmitters. It is the second most abundant mineral in the Earth's crust, and varieties of it include onyx, citrine, and amethyst. For 10 points, name this mineral mainly composed of silicon dioxide, with 
A rare, green-colored form of this mineral used in jewelry is called prasiolite. This mineral can possess planar deformation features, and one variety of this mineral is called chalcedony. It is at the bottom of Bowen's Reaction Series, and this mineral exhibits piezoelectricity, making it useful in watches and radio transmitters. It is the second most abundant mineral in the Earth's crust, and varieties of it include onyx, citrine, and amethyst. For 10 points, name this mineral mainly composed of silicon dioxide, with a Mohs hardness of 7.
A rare, green-colored form of this mineral used in jewelry is called prasiolite.