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White and Clear Crystal Identification: Telling Quartz From Its Look-Alikes

By Digital Towns Crystals · Last reviewed October 8, 2026

Short answer: a clear or white crystal is most often quartz, calcite, selenite (gypsum), apophyllite, halite, barite, howlite or glass. Start with hardness: quartz scratches glass, while calcite, gypsum, halite and barite cannot. Then check for a fingernail mark (gypsum), a doubled image (calcite), a salty taste (halite), unusual weight (barite) and a pearly sheen on flat faces (apophyllite). Bubbles and a perfectly smooth surface point to glass.

Colorless stones remove the one clue most people rely on. Without a color to go on, identification comes down to shape, weight, softness and how light behaves inside the piece, which is good news: those properties are far more reliable than shade ever was. Pure, unstained minerals of many species are colorless or white, so the list of candidates is longer here than for any other color (the color causes guide explains why impurities are usually what color a mineral in the first place).

Is it quartz, or something softer?

Settle that question first, because quartz is the default answer for a clear point and the most common thing a clear crystal is mistaken for. Minerals.net gives quartz a hardness of 7 and a specific gravity of 2.6 to 2.7, with no visible cleavage and a conchoidal fracture. That combination means three things you can check in a minute:

  • It scratches ordinary glass without being marked itself. Test on a back edge or a broken spot, never on a polished face.
  • It breaks in curved, shell-like chips, not flat steps. Geology.com lists the diagnostic properties of quartz as conchoidal fracture, glassy luster, hardness.
  • Natural crystals are six-sided prisms with horizontal striations across the prism faces and a pointed termination.

If a clear crystal fails the glass test, it is not quartz, whatever the label says. The rest of this page is about naming what it is instead.

Which soft white and clear minerals are the usual candidates?

Mineral Formula Mohs SG Best single clue
Quartz SiO2 7 2.6 to 2.7 Scratches glass, six-sided prisms
Calcite CaCO3 3 2.7 Rhombohedral cleavage, doubled image
Gypsum (selenite) CaSO4·2H2O 2 2.3 to 2.4 Fingernail scratches it; bends slightly
Halite NaCl 2 to 2.5 2.1 to 2.6 Cubes, salty taste, dissolves in water
Apophyllite KCa4Si8O20(F,OH)·8H2O 4.5 to 5 2.3 to 2.4 Pearly luster on the flat top face
Barite BaSO4 3 to 3.5 4.3 to 4.6 Heavy for its size, tabular blades
Howlite Ca2B5SiO9(OH)5 3.5 2.5 to 2.6 Chalky white with gray veining, usually tumbled

Two of these answers can be reached by hand alone. A fingernail is a calibrated tool: Geology.com puts it at 2 to 2.5 on the Mohs scale, so it will mark gypsum (hardness 2) but slide off calcite (3). And barite is the heavy one. Minerals.net notes that its name comes from the Greek barys, which means heavy, and its specific gravity of 4.3 to 4.6 makes a barite blade feel nearly twice the weight of a quartz or calcite piece the same size.

What do the individual tests tell you?

The doubled-line test for calcite

Lay a clear fragment over a printed line. If you see two lines, the piece is very likely calcite. Minerals.net records that transparent crystals exhibit strong double refraction, and that the clear Iceland spar variety shows it most strongly. Quartz is doubly refractive too, but far too weakly to see this way. Calcite also cleaves into slanted, six-faced rhombs, and Geology.com lists its diagnostic properties as rhombohedral cleavage, curved crystal faces, frequent twinning, and a powdered form that effervesces weakly in dilute HCl. An acid test belongs on a scrap or a powder, never on a display face.

The fingernail and the bend for selenite

Selenite is the transparent, crystalline variety of gypsum. Minerals.net describes gypsum as sectile and slightly flexible, with micaceous cleavage, and notes that crystals can be slightly bent, though they snap if pushed. A fingernail leaves a mark. That separates selenite from calcite instantly, and the selenite vs calcite comparison covers the finer points. Satin spar, the fibrous form, is a separate case covered in selenite vs satin spar.

Taste and water for halite

Halite is the only common mineral where tasting is a legitimate field test. Minerals.net lists its ID marks as a salty taste and being soluble in water, especially warm water. A touch of a damp fingertip to a corner, then to the tongue, settles it. Perfect cubes and cubic cleavage are the visual clue.

Luster for apophyllite

Apophyllite crystals look like glassy cubes or sharp four-sided pyramids. Minerals.net describes the luster as vitreous to greasy, and pearly on cleavage surfaces, which shows as a mother-of-pearl sheen on the flat top of a blocky crystal. Its hardness of 4.5 to 5 means it will not scratch glass reliably. The apophyllite vs quartz comparison is the page to read if your piece came from India and arrived labelled "quartz".

Decision table

What you observe Probable identity Next check
Scratches glass, six-sided striated prism Quartz Curved chips at broken edges
Shows two images of a line, breaks into rhombs Calcite Fizz test on powder
Fingernail scratches it, bends slightly Selenite (gypsum) Pearly, flexible cleavage flakes
Perfect cubes, tastes salty Halite Corner softens when wet
Pearly flat top, glassy sides, from Indian basalt Apophyllite Square cross-section, striated sides
Clear or white and heavy in the hand Barite Specific gravity above 4
Opaque, chalky white with gray veins Howlite Hardness 3.5, takes a high polish
Perfectly smooth, bubbles inside, no flaws Glass Feels warm; molded seams

Is a white stone dyed, coated or not a mineral at all?

White and colorless stones are the raw material for many dyed products, because a pale porous stone takes color evenly. Howlite is the standard example. Minerals.net reports that its white color is easily dyed, that it is dyed greenish blue to imitate turquoise, and that some dishonest dealers label dyed howlite as turquoise. The dyed howlite guide shows what to look for. The fine-grained alabaster form of gypsum is in the same position: Minerals.net describes it as porous and therefore easily dyed.

Clear quartz is also the base for metal-coated "aura" crystals, which carry a thin bonded film that shows rainbow colors at an angle and can wear off at edges. The opposite trick is glass sold as clear quartz. Glass has no crystal structure, so a "quartz" sphere or point with round gas bubbles, swirl lines or a perfectly flawless interior at a low price deserves suspicion. The glass imitations guide explains the loupe checks.

Which clear minerals react to water or handling?

Color change is rarely the issue with these minerals; physical change is. Halite dissolves, so it should never be rinsed or kept in a humid room. Gypsum can be scratched by a fingernail, so selenite wands and towers pick up marks from careless handling and should be dusted with a dry brush. Calcite is etched by acids, including acidic cleaners. Minerals.net also notes that anhydrite can absorb water and transform into gypsum, which is why some gypsum specimens show crumpled layers. Quartz is the robust one of the group and survives most cleaning.

Shopping the white and clear crystals we stock

Ask a seller to state the species, not just "clear crystal", and to include a photo of the crystal shape and base. For quartz, look for intact terminations and say whether the point is natural or polished. For soft minerals, check that shipping uses separate wrapping per piece, since apophyllite, selenite and calcite bruise on contact.

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Frequently asked questions

How can I tell clear quartz from glass?

Look for flaws. Natural quartz usually holds small inclusions, wisps or fractures, while glass can be flawless or show round gas bubbles and swirl marks. Quartz feels cool for longer, and a natural point has striations across its prism faces. A low price for a large, perfectly clear sphere is a warning sign.

Why does my clear crystal show a double image?

That is double refraction, and if it is strong enough to double a printed line, the crystal is almost certainly calcite, usually the clear variety called Iceland spar. Quartz bends light the same way but far too weakly to see without instruments.

Is selenite the same as satin spar?

Both are gypsum. Selenite is the transparent, crystalline form, usually in clear blades or plates. Satin spar is fibrous gypsum with a silky sheen, and many pieces sold as "selenite" wands and towers are cut from it. They share a hardness of 2 and the same care rules.

Can white crystals be dyed?

Yes. Howlite, white agate and alabaster are porous enough to take dye evenly, and dyed howlite is widely sold as turquoise. Dye tends to collect in cracks and veins. Quartz and calcite crystals are rarely dyed, but clear quartz is often coated to make aura quartz.

Which clear crystals should never get wet?

Halite dissolves, so keep it dry. Selenite and other gypsum pieces can be dulled and weakened by water. Calcite tolerates a quick rinse in plain water but not acidic cleaners. Apophyllite clusters are best dusted with a soft brush. Quartz is fine with water.

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