1Colour
What colour is it?
Multiple selections allowed.
Identify a specimen, one observation at a time.
Colour, hardness, streak, transparency — four field observations to narrow the index to a handful of likely candidates, the most common ones first.
2Hardness
How hard is it?
Try scratching the mineral.
3Streak
What colour is the powder?
Rub the mineral across an unglazed porcelain plate. The mark left behind reveals the true colour, independent of any impurities.
4Light
How does light behave?
Hold the mineral up to a light source, on a thin edge if possible.