6g Quartz Cluster
 
Quarts is one of the most common  minerals and a crystalline form of  silica (silicone dioxide) it comes in many varieties and colors such as clear , white , pink , brown, black , varieties with purple, red, green, blue, orange. 
It is widely used in jewelry, glass, electronics, food, abrasives, construction and more.
It's hardness is 7 on the Mohs scale