It appears to have been caused by the pressure of the internal crystal growth

Staurolite and Quartz Crystal

8 mm / 3x3x2 inches

appearing to have been precision cut by man and having a diamond-like geometrical shape

Color: Orange

Stibnite Crystal Spray | Shiny Metallic Mineral | 19 Gr | Xikuangshan Mine, China | SO24 Fluorescent It appears to have beenThis is an attractive shiny spray of metallic stibnite crystals from the Xikuangshan Mine of China. Stibnite is a lead gray mineral occurring as striated prismatic crystals, that are made up of antimony sulfide and is the main ore of antimony. It often forms groups of long, shiny metallic crystals radiating out at different angles. NOTE: Stibnite (antimony) is toxic and can be harmful if inhaled or swallowed. While a crystal sitting on your shelf