Analcime is a hydrated sodium-aluminum silicate generally classified within the zeolite group. Its standout visual feature is the formation of glassy white, colorless or pinkish pseudocubic crystals, particularly trapezohedra that can resemble rounded garnet crystals. Although individual crystals appear cubic to the eye, analcime can exhibit several lower-symmetry structural arrangements.
Analcime at a Glance
| Property | Analcime |
|---|---|
| Mineral group | Zeolite group; tectosilicate |
| Composition | NaAlSi₂O₆·H₂O |
| Colors | Colorless, white, gray, pink, greenish and yellowish |
| Crystal system | Variable; commonly pseudocubic with cubic or lower-symmetry ordering |
| Habit | Trapezohedral, granular, compact, massive and cavity-filling |
| Luster | Vitreous to sub-vitreous |
| Transparency | Transparent to translucent |
| Mohs hardness | 5–5.5 |
| Cleavage | Very poor or indistinct |
| Tenacity | Brittle |
| Common use | Mineral specimens, rare faceted collector gems and geological study |
| Main care concern | Brittle edges, internal fractures, matrix instability and rare-gem identification |
The ideal composition, hardness, brittle tenacity, very poor cleavage and common trapezohedral habit are documented in mineralogical references. Analcime crystals may look cubic macroscopically even when their detailed atomic ordering reflects tetragonal, orthorhombic, monoclinic or triclinic symmetry.
What Is Analcime?
Analcime is a framework silicate containing sodium and molecular water within its crystal structure. It forms a compositional series with pollucite, the cesium-rich analogue.
Although analcime is usually placed in the zeolite group, its framework is relatively compact compared with many zeolites. It occurs in volcanic cavities, alkaline igneous rocks, hydrothermal environments and altered sedimentary rocks.
Its mineral-family relationships are explained in the broader Zeolite guide.
Why Analcime Looks Cubic
Analcime commonly forms 24-faced trapezohedra that look isometric or cubic in hand specimens. The external appearance can remain pseudocubic even when microscopic ordering and slight distortion reduce the true symmetry.
This unusual crystallography has led to different crystal-system assignments in historical references. Modern descriptions recognize that specimens may exhibit several symmetry states without requiring separate mineral-species names.
The distinction matters when reading labels. A seller describing analcime as cubic is not necessarily wrong, but a technically precise description should acknowledge its variable ordering and pseudocubic appearance.
How Analcime Forms
Analcime commonly lines vesicles and cavities in basaltic or other silica-poor volcanic rocks. It crystallizes from late-stage fluids and may be associated with calcite, prehnite, quartz and other zeolites.
It can also form through alteration of volcanic glass, feldspathoids or clay-rich sedimentary material. In some sedimentary basins, analcime develops during burial and diagenesis rather than as a primary volcanic mineral.
The mineral is therefore encountered in several distinct geological settings:
- Cavities in basalt and phonolite.
- Alkaline pegmatites and nepheline syenites.
- Altered tuffs and volcanic ash beds.
- Authigenic grains in sandstone and siltstone.
- Hydrothermal veins and low-temperature mineral assemblages.
Each setting can produce different crystal sizes, colors and mineral associations.
Analcime Meaning and Symbolism
Analcime is traditionally associated with perspective, quiet observation and recognizing structure within complexity. Its nearly symmetrical external form is sometimes used symbolically to represent balance, while its variable internal symmetry can suggest that appearances do not always reveal complete structure.
Metaphysical traditions may claim that analcime improves clarity, communication or emotional balance. These are traditional beliefs rather than scientifically demonstrated effects.
A collector may still use the mineral as a visual reminder to examine a problem from more than one angle or to distinguish outward appearance from underlying evidence.
Important Analcime Localities
The type locality is the Cyclopean Islands near Aci Trezza and Aci Castello in Sicily, Italy, where the mineral was originally described from volcanic rock.
Mont Saint-Hilaire, Québec, is one of the world’s most important analcime specimen localities. The Poudrette quarry has produced sharp white to transparent trapezohedra associated with natrolite, serandite, polylithionite, aegirine and other alkaline-complex minerals. Fine individual crystals can reach several centimeters.
The Bay of Fundy region of Nova Scotia has produced transparent crystals suitable for rare faceting. Other significant occurrences include the Deccan volcanic province around Pune in Maharashtra, India; Val di Fassa in Trentino, Italy; Låven Island in Norway; Iceland; the Lake Superior copper district in Michigan; and several Scottish basalt localities.
Locality strongly affects specimen value. A small crystal from a classic or closed locality may command more than a larger but ordinary cavity specimen.
Analcime Compared With Other Zeolites
Analcime vs. Natrolite
Analcime usually forms equant trapezohedra, while natrolite is best known for slender needles and radiating sprays. Natrolite can be far more vulnerable to mechanical damage because its crystals are commonly thin and densely packed.
See the related acicular mineral in the Natrolite guide.
Analcime vs. Stilbite
Stilbite typically forms pearly bladed crystals in fan-shaped or sheaf-like aggregates. Analcime is generally more glassy and equant, with distinct pseudocubic outlines.
The contrast in crystal habit is covered in the Stilbite guide.
Analcime vs. Apophyllite
Apophyllite commonly forms square or rectangular prisms with prominent basal cleavage and a brighter pearly-to-vitreous luster. Analcime lacks apophyllite’s characteristic cleavage plates and usually forms trapezohedra rather than square prisms.
Explore the differences in the Apophyllite guide.
Is Analcime a Gemstone?
Transparent analcime can be faceted, but gem-quality rough is rare and the finished stones are collected mainly by specialists in unusual mineral species.
Most faceted examples are:
- Colorless or very pale.
- Approximately 0.5–2 carats.
- Cut as ovals, cushions, rounds or step cuts.
- Slightly included or hazy.
- Purchased for mineral rarity rather than exceptional brilliance.
Specialist dealers have documented transparent faceted stones around 1–2 carats from Skardu, Pakistan, and Nova Scotia. One rare-gem dealer listed a 1.05-carat included Nova Scotia stone at about $30 per carat, while contemporary specialist listings confirm that clean transparent material remains unusual.
Analcime’s hardness of 5–5.5 is sufficient for a carefully protected pendant or collector ring, but its brittleness and rarity make routine wear impractical. A faceted stone is generally more valuable as a documented species gem than as a conventional jewelry stone.
How Analcime Is Sold
The majority of analcime reaches the market as mineral specimens rather than lapidary rough.
Common sales formats include:
- Thumbnail specimens containing one crystal under about 3 cm.
- Miniatures with several crystals and associated zeolites.
- Cabinet specimens from basalt cavities.
- Mont Saint-Hilaire combinations with rare alkaline minerals.
- Rare transparent crystals reserved for faceting.
The exact association can matter as much as the analcime itself. A sharp crystal on natrolite or serandite from Mont Saint-Hilaire may be priced as a locality specimen rather than by size or weight.
Analcime Price and Value
There is no standardized analcime price per gram or carat because specimen aesthetics and locality dominate the market.
Indicative retail asking-price ranges are:
| Analcime form | Approximate retail range |
|---|---|
| Small common specimen or thumbnail | $10–$50 |
| Good miniature with distinct crystals | $50–$150 |
| Fine locality or combination specimen | $150–$500 |
| Exceptional Mont Saint-Hilaire or museum-quality piece | $500–$2,000+ |
| Included faceted collector stone | About $30–$75 per carat |
| Cleaner or precision-cut rare faceted stone | About $75–$200+ per carat |
Current listings include ordinary specimens around $30–$90, a 38.9-gram English cluster near $50, a 25 mm Mont Saint-Hilaire piece around $54 and a sharp 3.4 cm Québec crystal offered near $320. Exceptional combination specimens may be priced far higher.
The faceted range is less stable because so few stones reach the market. Published specialist inventory has shown included analcime near $30 per carat, while better transparency, precision cutting and verified locality can justify substantial premiums.
These figures are asking-price guides rather than appraisals. Damage, repairs, crystal completeness, locality documentation and associated minerals can change value more than weight alone.
How to Identify Analcime
The strongest visual clue is a white, colorless or pale trapezohedral crystal with vitreous luster in a volcanic cavity or alkaline-rock association. Analcime can also occur as granular or massive material with little diagnostic external form.
It may be confused with:
- Leucite, which also forms trapezohedral crystals.
- Pollucite, its cesium-rich series partner.
- Calcite, which is softer and has prominent cleavage.
- Garnet, which is harder and lacks water in its structure.
- White fluorite, which has octahedral cleavage.
- Other pale zeolites with different habits.
Definitive separation may require refractive index, density, optical testing, Raman spectroscopy or X-ray diffraction. The non-destructive starting process is described in How to Identify Crystals.
Analcime Hardness and Durability
Analcime has a Mohs hardness of 5–5.5, making it harder than calcite and fluorite but softer than feldspar and quartz. Compare its scratch resistance with common gems using the Gemstone Hardness Chart.
Very poor cleavage reduces the tendency to split cleanly, but the mineral remains brittle. Crystal edges can bruise, chips may develop around contact points and matrix-bound specimens can detach after impact.
Large crystals should be supported from beneath rather than held by exposed faces. A specimen containing delicate natrolite, stilbite or calcite may require more conservative care than the analcime itself.
Can Analcime Go in Water?
Analcime is not readily soluble in brief contact with clean water, but routine soaking is unnecessary. Matrix minerals, repairs, iron staining or delicate associated zeolites may react differently.
Do not use acids to remove calcite or matrix unless the entire mineral assemblage has been professionally evaluated. Acid can destroy associated minerals and permanently alter specimen surfaces.
How to Clean Analcime
A stable single crystal can be dusted with a soft brush and, when necessary, rinsed briefly in lukewarm water. Dry the specimen at room temperature without rubbing crystal edges.
Avoid ultrasonic cleaners, steam, abrupt temperature changes and prolonged soaking. Do not use compressed air on specimens with needle-like zeolites or weak matrix.
For an important Mont Saint-Hilaire or classic-locality specimen, minor surface dust is preferable to irreversible cleaning damage.
Buying Analcime
Confirm the locality and preserve any original collection label. A specimen from Mont Saint-Hilaire, the Cyclopean Islands or a documented Bay of Fundy occurrence may carry historical and mineralogical value beyond its appearance.
Inspect photographs for chipped crystal corners, contact damage, glue lines and crystals reattached to matrix. Repairs are common in complex specimens but should be disclosed.
Faceted stones should include enough gemological information to separate analcime from quartz, feldspar, glass and other colorless species. A laboratory report may cost more than a small stone, but it is appropriate for an unusually clean, large or expensive example.
Frequently Asked Questions
Is analcime a zeolite?
Yes. It is generally classified within the zeolite group, although its compact framework differs from the more open structures of several familiar zeolites.
Why does analcime look cubic?
Its external crystals are usually pseudocubic trapezohedra. Slight variations in silicon-aluminum ordering can reduce the true internal symmetry without changing the obvious hand-specimen shape.
Is analcime rare?
The mineral is widespread, but transparent faceting rough and sharp crystals from important localities are much less common.
Can analcime be faceted?
Yes. Colorless transparent crystals are occasionally faceted, usually into small collector stones rather than commercial jewelry gems.
Is analcime safe to handle?
Stable intact specimens can be handled with normal mineral-care precautions. Avoid inhaling dust from cutting or grinding any silicate mineral.
Does analcime fluoresce?
Some specimens fluoresce greenish, white or yellow under ultraviolet light, but fluorescence varies and does not confirm identity by itself.
Can analcime be worn every day?
It is not recommended for routine ring wear. Its moderate hardness, brittleness and rarity make pendants or protected collector settings more appropriate.
- Analcime has the ideal composition NaAlSi₂O₆·H₂O, a hardness of 5–5.5 and very poor cleavage.
- Analcime may exhibit cubic or several lower-symmetry structures while retaining a pseudocubic external appearance.
- The Cyclopean Islands near Sicily constitute the mineral’s type locality.
- Mont Saint-Hilaire has produced major analcime specimens associated with natrolite, serandite and other alkaline-complex minerals.
- Transparent analcime is sufficiently uncommon that faceted stones are primarily collected as rare mineral species.
Find it in Crystals That Start With A or browse more mineral profiles in the Gemstone Guides collection.
