Herkimer diamond (quartz) crystal. Herkimer diamonds are a hydrothermal formation of quartz. This crystal weights 3.25 grams and measures 1.5cm x 1.5cm x 1cm. Mined by myself in my herkimer diamond claim. Diamond Acres in Fonda, NY is where my herkimer diamond claim is located. We also find calcite and dolomite druzzy at this location.