6 Hardness TestScratch a mineral with either another mineral or field test materials. The harder mineral will leave a mark or cut into the softer mineral.Field TestTry to scratch withFingernail - if so, 2.5if not,Copper Penny – if so, 3Steel Nail – if so, 5Glass Plate – if so, 5.5Streak Plate – if so, 7.5if not, > 7.5
7 Very soft mineralsWhite – kaolinite – sticks to tougue, feels dry and powderyWhitish pink – talc – feels smoothDark gray – graphic – feels smooth, rubs off on fingers
8 Very hard minerals Clear – diamond Hexagonal – corundum (red: ruby, blue: sapphire)
9 StreakRub the mineral across the porcelain plate. The color left behind is the streak. Nonmetallic minerals and those that have a hardness greater than the streak plate will leave either white or no streak.
10 Cleavage vs. FractureSheets – mica: biotite (black – dark brown) and muscovite (light colored)Pink – orthoclase feldspar