Digital TownsCrystalsShop crystals
  1. Crystals & Minerals
  2. Stilbite

Stilbite: The Bow-Tie Zeolite, Explained

By Digital Towns Crystals · Last reviewed October 8, 2026

Short answer: stilbite is a calcium sodium zeolite, a water-bearing aluminosilicate that grows in gas cavities of basalt. It is soft (3.5 to 4 on the Mohs scale), light (specific gravity about 2.15) and nearly always grows as sheaves that pinch in the middle like a bow tie. Most collector stilbite today is peach, pink or white material from the Deccan basalts of Maharashtra, India.

What is stilbite, chemically?

Stilbite belongs to the zeolites, a family that the U.S. Geological Survey describes as hydrated aluminosilicates of the alkaline and alkaline-earth metals. Picture a rigid scaffold of silicon, aluminum and oxygen with open channels running through it. Calcium, sodium and loosely held water molecules sit inside those channels rather than being locked into the frame. That loose water matters for the collector: it is why stilbite turns chalky if it is baked, and why the mineral is light in the hand.

The formula given by Webmineral for the common species is NaCa4[Al8Si28O72] with 28 to 32 water molecules. Strictly, "stilbite" is now a series name. In 1997 the zeolite subcommittee of the International Mineralogical Association split it into two species, and Minerals.net notes that almost all stilbite in collections is the calcium-dominant member, stilbite-Ca. The sodium member, stilbite-Na, is scarce and tends to turn up in basalt near the sea. A dealer label that just says "stilbite" is fine; nobody expects a chemical analysis on a $40 cluster.

Property Stilbite-Ca
Crystal system Monoclinic
Mohs hardness 3.5 to 4
Specific gravity about 2.15
Cleavage One perfect direction, {010}
Luster Vitreous, pearly on the cleavage face
Streak White
Usual colors White, cream, peach, pink, orange, brown

The name comes from Greek. Webmineral derives it from the Greek stilbe, "luster", in allusion to the pearly to vitreous luster, while the IZA Commission on Natural Zeolites ties it to the Greek word for mirror. Either way, the point is the shine on the broken flat faces, and you can see it: tilt a stilbite sheaf under a lamp and the cleavage surfaces flash with a soft, mother-of-pearl sheen that the crystal sides do not have.

Why does stilbite grow in bow ties?

Single, separate stilbite crystals are rare. What you see on almost every specimen is a bundle of thin, tabular blades that share a common waist and fan out at both ends. Webmineral's habit list includes "Wheat Sheaf", bundle shaped aggregates resembling wheat sheafs after hand reaping wheat, which is exactly the look. When the bundle is short and fat it reads as a bow tie; when it radiates all the way around it becomes a ball or rosette.

The bundling comes from the way the crystals twin and branch as they grow. The IZA datasheet shows a single stilbite crystal divided into growth sectors with fine twinning in several of them, so what looks like one blade is internally a composite. For a buyer the practical takeaways are simple:

  • Sharp, separated blade tips at both ends of a sheaf show the crystal grew freely into open space.
  • Doubly terminated sheaves that sit loose or perch on another mineral are prized, because they grew without a base.
  • A frosted or crushed waist usually means the sheaf was pried off a wall and later glued back.

Where do the best stilbite specimens come from?

Stilbite grows in cavities of basaltic lava and similar rocks worldwide, but a few places set the standard. The IZA datasheet lists crystals up to 10 cm from the classic localities of Teigarhorn and Roudafell in eastern Iceland and Nasik and Pune in India, along with the Faroe Islands, Nova Scotia, the Glasgow area and the quarries around Paterson, New Jersey.

Region What it is known for
Maharashtra, India (Pune, Nashik, Jalgaon, Aurangabad) Peach to pink sheaves with apophyllite, the bulk of today's supply
Berufjord, Iceland Classic white and cream sheaves, historically important
Paterson and Prospect Park, New Jersey Large bow ties and wheat sheaves from old trap rock quarries
Bay of Fundy, Nova Scotia Orange to white crystals from coastal basalt
Malmberget, Sweden Brownish-yellow crystal plates

Minerals.net calls India's Maharashtra deposits the largest and most significant finds, and names Paterson and Prospect Park in Passaic County as the foremost American source of large bow-ties and wheat sheaves. Material from the Indian quarries dominates the market because road-building there keeps opening fresh basalt. For the geology behind that supply, see the Deccan Traps origin guide.

The host rock matters too. According to the IZA datasheet, stilbite-Ca tends to occur in tholeiitic basalt or basaltic andesite because of its relatively high silica content. In eastern Iceland it sits in the deepest of the zeolite zones mapped in the lava pile, and similar assemblages form in the Reykjavik geothermal fields at about 90 to 110 °C. In other words, stilbite is a warm-water mineral, not a magmatic one: it formed long after the lava froze.

How do you tell stilbite from heulandite and other look-alikes?

The mineral most often confused with stilbite is heulandite, which grows in the same cavities, comes in the same peach and cream colors and has nearly the same hardness and density. The Minerals.net heulandite page sums up the problem bluntly: stilbite forms in a different crystal shape; otherwise difficult to distinguish. So shape is the test.

Clue Stilbite Heulandite
Typical shape Sheaves and bow ties of thin blades Single tabular crystals shaped like an old coffin
How crystals sit Bundled, pinched at the waist Separate, often in parallel groups
Luster Pearly on the cleavage Pearly on the cleavage
Hardness 3.5 to 4 about 3.5 to 4

Other checks:

  • Stellerite forms very similar sheaves but more often perfect hemispherical balls. Without analysis, a ball-shaped "stilbite" may be stellerite.
  • Apophyllite is harder (about 4.5 to 5), glassy rather than pearly on its sides, and grows as blocky pseudo-cubes or pointed prisms.
  • Scolecite and mesolite are needle zeolites; they never form flat blades. Our scolecite guide covers those.

Minerals.net also notes that stilbite is occasionally fluorescent yellow in UV light. Most Indian peach stilbite shows little or nothing under a shortwave lamp, so a dull response proves nothing either way.

What do peach, pink and white stilbite mean for value?

Color is the first thing buyers notice and the main thing sellers name. Stilbite itself is colorless when pure; the warm tones come from trace impurities picked up during growth. Graham Wilson's Turnstone note on Pune specimens describes the material as commonly pale "pink", adding that in some lights the hue is more a pale orange than a delicate pink. That is the "peach" of the trade.

Price follows contrast and condition more than color alone. Strong peach sheaves set against green apophyllite or dark basalt sell for more than the same sheaves on a gray crust. White stilbite is common and usually cheaper unless the crystals are unusually large or glassy. A deep salmon or orange color with good luster is a premium feature.

Is stilbite treated or faked?

Stilbite is too cheap and too fragile to be worth synthesizing, so outright fakes are rare. The tricks are cosmetic:

  • Reassembly. Sheaves knocked loose in the quarry get glued back, sometimes onto a different matrix. Look for glossy glue lines at the base and a sheaf whose color does not match its neighbors.
  • Dyeing. Bright pink or red "stilbite" with color pooled in cracks deserves a close look with a 10x loupe.
  • Oiling. A wet-looking surface on matrix can be oil wiped on to darken the basalt and boost contrast.

How should stilbite be cleaned and stored?

At 3.5 to 4, stilbite is softer than a steel knife and easily bruised. The blades split along their perfect cleavage, and the delicate tips break if a specimen is set down on its face. Hold pieces by the matrix, store them so nothing rests on the crystals, and clean with compressed air or a soft brush. Plain water does not dissolve stilbite, but soaking can loosen dirt into cracks and stain the pearly faces; skip ultrasonic cleaners and heat entirely. For deeper care steps that apply to the whole family, see the apophyllite guide.

Stilbite in crystal traditions

In crystal traditions, stilbite is associated with creativity and with gentle, steady energy, and peach stilbite is often paired with apophyllite in collections built around the Indian combination. These are cultural associations, not properties a geologist would test.

Shopping for stilbite: what to look for

Judge a stilbite specimen on four things: sharp sheaf tips at both ends, a clean waist without glue, good contrast with whatever it sits on, and a stated locality. Weight and dimensions should be listed, because a cabinet piece over a kilogram needs real shelf space. Examples currently in stock:

Digital Towns Market

Stilbite in stock

See all crystals and minerals

Frequently asked questions

Is stilbite a rare mineral?

No. Stilbite is one of the more common zeolites and turns up in most of the world's basalt zeolite districts. What is uncommon is a large, undamaged sheaf with strong color and clean contrast against apophyllite or matrix. Those specimens command real prices, while small white clusters stay inexpensive.

Can stilbite go in water?

Stilbite does not dissolve in water, so a quick rinse will not destroy it. The risk is to the matrix and the pearly cleavage faces, which can stain or loosen when soaked. A soft brush and compressed air are the safer routine, and heat or ultrasonic cleaners should be avoided completely.

What is the difference between peach stilbite and pink stilbite?

They are the same mineral. Dealers use peach, pink, salmon and orange for overlapping shades of warm stilbite, and the same crystal can look pinker or more orange depending on the light. Judge by the specimen photos in daylight rather than by the color word in the title.

How hard is stilbite?

Stilbite rates 3.5 to 4 on the Mohs scale, about the same as a copper coin to fluorite. A steel knife scratches it, and the blades split easily along their one perfect cleavage, so it is a display mineral rather than something to carry or tumble.

Why is stilbite so often sold with apophyllite?

They grow in the same basalt cavities in India, frequently on the same specimen, with apophyllite crystals perched on or beside stilbite sheaves. The color contrast between peach stilbite and clear or green apophyllite is what makes these pieces popular with collectors and decorators.

Sources