Minerals The minerals quartz and gypsum are very similar in terms of appearance. If you ran across a white-ish sample while on a hike, what's the easiest way to tell whether the sample is quartz or gypsum?

a) Taste it - gypsum tastes salty.
b) Scratch it with your fingernail - gypsum is much softer.
c) Use acid - gypsum will react, quartz will not.
d) By heft - quartz is much more dense than gypsum.