Turquoise
Ask two people whether turquoise is blue or green and you will get three answers and one person leaving.
Flint
Flint is the only rock that complains when hit, and it does so with sparks.
Pumice
Pumice is a rock that floats on water, a habit the other rocks regard as showing off.
Quicksand
A person cannot sink completely into quicksand; it is too dense, and they would float at about the waist.
Diamond
A diamond is made of the same carbon as pencil lead, and it can burn.
Stepping stone
Every set of stepping stones contains exactly one wobbly stone, and it is never the one you tested.
Volcano
A volcano is a mountain that keeps the inside of the Earth on the outside, where it can be kept an eye on.
Stalactite
A stalactite is a rock that grows down from a cave ceiling, holding on tight, and waiting for a stalagmite that is taking its time.
Cave
A cave is made almost entirely of the rock that isn’t there, plus an echo.
Stalagmite
A stalagmite grows upward about a centimetre a century, and has no plans for when it gets there.