Rock Crystal is the clear or white name for quartz, or at least it's one of the most common. This gem is an elongated clear quartz with an error that looked cool; the gouge along the back is from the saw blade when I was cutting the preform. Rather than perfection, I chose to keep the error; I thought it added to the stone.
Diameter 25.5 mm by 8.5mm; 2.77g or 13.8ct weight.