Water Safe Crystals

Water safe crystals chart

This water safe crystals chart covers the stones people ask about most. Quick rinse means lukewarm water, a few seconds, then dry at once. Wipe only means a damp cloth and nothing more.

Crystals that can go in water

Crystals that can go in water are mostly hard minerals, around Mohs 6.5 and up, with no pores and no reaction to water. A rinse in lukewarm water with a drop of mild soap is fine for all of these. A common rule says anything at 6 or above is water safe, but pyrite at 6 to 6.5 rusts and opal at 5.5 to 6.5 is porous, so check the mineral as well as the number.

Clear, milky, smoky and rose quartz, plus amethyst and citrine.
Agate, carnelian, jasper and other chalcedony.
Aventurine and tiger's eye.
Black tourmaline, garnet, topaz and beryl.
Kunzite and moonstone, rinsed and dried promptly because both cleave.
Kyanite, which does not dissolve but splits along its blades, so rinse it and skip long soaks.

Crystals that cannot go in water because they dissolve

Crystals that cannot go in water at all are the soluble ones, and they dissolve slowly enough that the damage sneaks up on you.

Selenite and satin spar, both gypsum. About 2 grams of gypsum dissolves in a liter of water, enough to round edges and dull the sheen.
Desert rose: plates of gypsum or baryte bound with sand, which loosens and crumbles when wet.
Halite, which is rock salt and dissolves in minutes.
Celestite: strontium sulfate, only slightly soluble, but soft and quick to cleave, so give it a quick rinse at most and never a soak.

Soft crystals that split in water

Soft crystals that split along cleavage planes do not dissolve, but water, temperature swings and scrubbing find their weak spots.

Fluorite: Mohs 4 with perfect cleavage. A quick lukewarm rinse is fine, but hot water can crack it.
Lepidolite: a layered mica that can flake when water works between its sheets, so wipe raw pieces and give polished ones a quick rinse at most.
Apophyllite: Mohs 4.5 to 5 with perfect cleavage. Rinse briefly and dry fast.
Stilbite: a soft zeolite that grows in fragile sprays. Rinse gently and never scrub.
Scolecite: fine zeolite needles that snap under a brush or a hard spray of water.
Larimar: Mohs 4.5 to 5. Rinse and dry, no long soaks.

Porous and organic crystals

Porous and organic crystals take in water along with whatever is dissolved in it, or react to the heat and chemicals that often come with cleaning.

Pink opal: opal holds water in its structure, and porous opal can soak up more and cloud, so a quick rinse at most, never a soak.
Amber: fossil resin at Mohs 2 to 2.5. A quick lukewarm rinse is fine, but hot water, alcohol and perfume damage it.
Ammonite: a fossil shell turned to calcite, aragonite or sometimes pyrite. A quick rinse at most, never a soak, and keep pyrite ammonites dry.
Gem silica: the hard chalcedony is fine with a rinse, but softer chrysocolla patches are porous, so keep it brief.
Malachite, azurite, turquoise and chrysocolla: soft, porous copper minerals. Wipe with a damp cloth, then dry.

Crystals that rust

Crystals that rust are iron sulfides, and damp air alone can start the damage.

Pyrite: iron sulfide at Mohs 6 to 6.5. Water and humidity slowly turn it into rusty iron sulfate and sulfuric acid, so dry brush it only, and store it with a silica gel pack in a humid home.
Marcasite: a less stable form of the same iron sulfide, which can crumble to powder in a damp drawer.

Selenite in water

Selenite in water slowly dissolves, because selenite is gypsum, a soft calcium sulfate that water carries away a little at a time. A splash will not ruin it, but soaking frosts the satin surface, rounds the edges and can leave the piece pitted, so dry it right away with a soft cloth. It sounds odd, since the giant selenite crystals of Mexico's Naica mine grew underwater. That water was hot and already saturated with calcium sulfate, and tap water is not. Mindat's selenite page has the mineral data.