Dilute hydrochloric acid test is important to distinguish between calcite (which effervesces) and dolomite (which does not, unless powdered).

Test to see if a magnet is attracted to the mineral (e.g., magnetite).

Striations (very thin, parallel grooves) allow plagioclase to be positively identified and distinguished from potassium feldspar.

The striations are only present on one of the two sets of cleavage planes – check both sets!

Don’t confuse the striations with differently colored intergrowths or veinlets seen on cleavage faces of some potassium feldspar specimens, but these have variable widths, are not strictly parallel, and are not grooves.

Halite = salty taste

Odor = breath on kaolinite = wet dirt, earth smell; powder of some sulfide minerals = rotten eggs.

Feel = talc feels slippery.

Tenacity or toughness – resistance to being broken.

Brittle minerals shatter when broken (e.g., quartz).

Flexible minerals can be bent without breaking, but will not resume the original position (e.g., chlorite).

Elastic minerals can be bent without breaking and will spring back (e.g., micas).

Malleable minerals can be hammered into thin sheets (e.g., copper, gold).

Sectile minerals can be cut with a knife (e.g., gypsum).