The four tools
A hardness kit: glass plate (5.5), steel knife (5.5), copper coin (3.5), fingernail (2.5). A white porcelain streak plate. A dropper bottle of 10% HCl (or vinegar for patient testing). A small magnet. Four items, pocket-sized, and they resolve almost every common specimen.
How the tests flow
Streak first (color on porcelain — hematite is red, magnetite black, most everything else white). Hardness second (glass, knife, coin, nail). Acid third (fizz = calcite family). Magnet fourth (magnetite). Each test eliminates candidates; three tests usually leave one name standing.
The lookalike discipline
The moment you are certain is the moment to run one more test: quartz vs calcite (the fizz), Downy vs Hairy (the bill), shale vs slate (the ring). The lookalike warnings in this library exist because every collector misidentifies the first three of each pair — the tests are how it stops at three.