Overview

Analcime is a zeolite-group tectosilicate best known for its distinctive trapezohedral crystals that look almost cubic. Most specimens are colorless to white or gray, occasionally faintly pink or honey toned, and range from frosty matte “snowballs” to sharply lustrous glassy crystals. It typically forms in the cavities of basaltic lavas and tuffs (zeolite facies) and in alkaline intrusive rocks (syenites and related). Classic associations include natrolite, thomsonite, chabazite, heulandite, laumontite, prehnite, calcite, and, in alkaline complexes, aegirine, arfvedsonite, and microcline.

Collectors prize analcime for its crisp crystal geometry, elegant contrasts on dark basalt or with black-green aegirine, and the breadth of world localities that yield handsome cabinet pieces at approachable prices. While common as a species, top-quality aesthetics—high luster, sharp edges, large size, and attractive matrix—are much rarer and command strong interest.

Popularity

Analcime holds a special place among zeolite collectors and lovers of classic volcanic minerals. Its pseudo-cubic trapezohedra are textbook forms that instantly read “geology,” and famous localities like Mont Saint-Hilaire and the Cyclopean Islands have produced generations of display pieces. Because it occurs widely, there is material for every budget—from inexpensive basalt vugs with small crystals to dramatic museum plates where lustrous white or colorless forms perch on jet-black aegirine. The species remains popular for its clean lines, soothing palette, and the variety of natural “compositions” it creates with partner minerals.

Top Collecting Localities

While analcime is global in distribution, a handful of regions have produced especially desirable and iconic specimens. Below are some of the best-known locales with consistent track records for high-aesthetic material.

Mont Saint-Hilaire, Canada

Mont Saint-Hilaire (Québec) is a world-class alkaline complex famous for its diverse species and striking contrasts. Analcime here often forms sharp, highly lustrous trapezohedra from thumbnail to large cabinet size, typically perched on black-green aegirine, albite, or microcline. Many pieces show exceptional form and brightness, sometimes with delicate sprays of natrolite, creating dramatic black-and-white displays. The combination of crystal quality, associations, and provenance makes MSH analcime among the most collectible in the world.

Collector’s Guide

Evaluating Specimen Quality

• Color and Transparency:

  • Most valued are colorless to bright white crystals with a uniform tone. Subtle gray or pinkish hues can be attractive; brownish or dingy tones are less desirable unless offset by superb form.
  • Translucency to partial clarity adds life. Completely opaque “chalky” crystals can still be fine if the faces are sharp and the composition is aesthetic.

• Luster:

  • Top pieces show a vitreous to satiny sheen on clean faces. A dull or etched surface will reduce impact unless balanced by exceptional associations or rare size.

• Crystal Form and Size:

  • Look for well-defined trapezohedra with crisp edges and complete terminations. Blunted or heavily etched faces are common but less desirable.
  • Larger crystals (2–5 cm and up) with full symmetry are uncommon and sought-after, particularly from Mont Saint-Hilaire and classic basalts.

• Associations and Matrix:

  • Strong contrasts add value. Examples include:
    • White analcime on dark basalt, with chabazite or thomsonite accents.
    • Glassy analcime perched on black aegirine spikes (Mont Saint-Hilaire).
    • Natrolite sprays or calcite scalenohedra offering texture and sparkle.
  • Balanced compositions with a primary, undamaged crystal as a focal point generally command premiums.

• Condition:

  • Inspect edges and corners—small chips on bright white crystals can show starkly.
  • Check for bruising where vug minerals grew crowded. Minor back-side contacts are acceptable; obvious front-face damage is not.
  • Stability matters: analcime can be brittle; avoid pieces with internal cracks that cross major faces.

• Rarity and Provenance:

  • Localities with historic significance (Cyclopean Islands, classic Faroe/Iceland coastal sites, Mont Saint-Hilaire) enhance desirability.
  • Documented pocket or quarry provenance is a plus for advanced collections.

Detecting Repairs or Treatments

• Repairs:

  • Reattachments are possible where crystals detached from matrix. Use a loupe to spot thin, glossy glue films at the matrix junction or a straight seam around a crystal’s base. Some epoxies fluoresce under longwave UV.
  • Multiple crystals on a matrix? Compare alignment of growth striations and contact textures—misfits can suggest assembly.

• Treatments:

  • Analcime is rarely treated. Avoid aggressive polishing; polished faces look unnaturally glassy and lack natural micro-growth textures. Any such work should be disclosed.
  • Coatings are unusual; uneven sheen or “plastic” look in recesses can indicate a surface application.

Care and Storage

• Handling:

  • Analcime is moderately soft and brittle (about Mohs 5–5.5). Handle by the matrix, not the crystal edges. Support larger vug pieces with both hands.

• Cleaning:

  • Dust gently with a soft brush or air bulb. For grime or fingerprints, use lukewarm water with a drop of mild soap; gently swish and rinse thoroughly.
  • Avoid acids and harsh chemicals—these can attack zeolite surfaces or sensitive matrix species.
  • Do not use ultrasonic or steam cleaners; vibration and heat can fracture crystals or compromise repaired joins.

• Light and Temperature:

  • Natural colors are generally light-stable. Normal display lighting is fine; avoid prolonged direct sunlight and high-heat environments that can stress the crystal or dehydrating matrices.
  • Avoid rapid temperature swings which can induce cracks.

• Storage and Display:

  • Provide padding in drawers or display stands. Keep pieces separated to prevent abrasion; analcime can both scratch softer species and be scratched by harder ones.
  • Use small amounts of museum putty for stability on shelves, especially in vibration-prone settings.
  • Label provenance—locality and pocket information add lasting value.

With mindful selection—favoring sharp form, bright luster, strong contrasts, and solid condition—analcime can anchor an eye-catching zeolite suite or stand proudly as a sculptural, minimalist centerpiece.