Overview

Jeremejevite is an exceptionally rare aluminum borate [Al6B5O15(OH)3F] from granitic pegmatites, most famous for its delicate sky-blue to colorless prisms and razor-sharp terminations. Well-formed crystals are typically slender hexagonal prisms, often transparent to gemmy with bright vitreous luster. The species is a connoisseur favorite: it combines extreme rarity with refined aesthetics—clean, icy prisms that can look “aquamarine-like,” yet with a subtly different tone and stronger pleochroism. The best pieces, especially those from Namibia’s Erongo pegmatites, feature lustrous, gem-clear crystals standing free or perched on contrasting white albite with black schorl, making for striking displays. Even small, undamaged crystals are highly sought, and fine matrix specimens are genuinely scarce.

Popularity

For decades after its 19th-century discovery in Transbaikalia, Russia, jeremejevite remained a mineralogical curiosity known mainly from tiny fragments. Its reputation transformed after notable finds in Namibia in the late 1990s–2000s, which produced elegant, transparent crystals with soft blue hues and textbook terminations. Those pockets vaulted jeremejevite into the upper tier of rare gem species collected for aesthetics, not just rarity. While the overall supply remains small, the Namibian discoveries made it possible for serious collectors to acquire fine single crystals and the occasional matrix piece. Cut stones exist but are scarce and expensive; as specimens, clean crystals over a few centimeters are rare prizes, and attractive small thumbnails can command strong prices due to the species’ prestige and fragility.

Top Collecting Localities

Below are several classic sources that have produced collectible jeremejevite, each with a distinct look and history. Only localities with verified IDs are included.

Erongo Mountains, Namibia

Erongo is the modern benchmark for jeremejevite. Crystals range from colorless to soft pastel blue, commonly as slender, transparent prisms with brilliant luster and sharp basal or pyramidal terminations. Aesthetics are enhanced by classic pegmatite associations—white albite blades, black schorl tourmaline, and occasional smoky quartz—creating strong visual contrast. While most crystals are singles or small clusters, a few choice matrix pieces exist and are highly coveted. Collectors prize Erongo specimens for clarity, crisp form, and the serene, “icy” palette that displays beautifully even in modest sizes.

Ameib Farm 60, Namibia

Within the broader Erongo area, Ameib Farm 60 is well-known among collectors for producing some of the most elegant jeremejevite crystals. Typical pieces show perfectly limpid, colorless to pale-blue prisms with brilliant luster, sometimes perched on snow-white feldspar. Terminations tend to be razor-sharp and flat to slightly complex. Due to the brittleness of the species, truly undamaged Ameib crystals are scarce, and clean singles with top luster are often preferred even over repaired matrix. The best thumbnails and small miniature singles from Ameib are considered type examples of “textbook” jeremejevite.

Collector’s Guide

Evaluating Specimen Quality

• Color and Transparency: The most desirable jeremejevite ranges from colorless to delicate sky blue. Stronger blue is scarce and prized if the crystal remains bright (not overly saturated or gray). High transparency is a key value driver—gem-clear interiors with minimal veils or cracks are ideal. Backlighting should make the crystal “glow,” but it should also look lively in ambient case lighting.

• Luster and Termination: Seek bright, vitreous luster on the prism faces and crisp, undamaged terminations. Flat basal terminations that reflect like mirrors are especially attractive; more complex pyramidal tips can add interest. Minute chips stand out on this species, so examine tips and edges carefully under magnification.

• Crystal Form and Size: Classic jeremejevite forms slender hexagonal prisms, often 1–3 cm; anything over ~4–5 cm that is clean and undamaged becomes significantly rarer. Slightly stouter crystals exist and can be very showy if proportions are balanced. Even tiny thumbnails can be superb if they are perfect and vividly lustrous.

• Matrix and Associations: Matrix greatly enhances aesthetics and value when present: white albite and black schorl emphasize the crystal’s glassy clarity, and occasional smoky quartz adds drama. However, due to the brittle nature of jeremejevite, many matrix pieces are repaired; pristine, unrepaired matrix examples carry a premium.

• Condition: Condition is paramount. The species is brittle and commonly exhibits stress fractures. Favor pieces with pristine tips and minimal edge wear. Small “flea bites” at edges can reduce value disproportionately on such a rare, gemmy species. Well-disclosed, neat repairs may be acceptable on significant pieces but should lower the price relative to an unrepaired equivalent.

• Overall Aesthetics: Step back and judge composition and impact. Does the crystal stand or point pleasingly? Is there appealing contrast with matrix? Do color and luster “read” well without backlight? A small, perfectly proportioned, high-luster crystal can outshine a larger, included, or dinged piece.

Detecting Repairs or Treatments

• Repairs/Reattachments: Repaired tips and reattached crystals are not uncommon, especially on matrix. Inspect for straight hairline seams, misaligned striations, or glossy glue at junctions. Longwave UV can sometimes reveal epoxy fluorescence. Ask for disclosure; “one clean repair” is common on larger matrix pieces, but zero repairs command a premium.

• Polished Terminations: Polishing to mask a chip is rare but possible. Natural terminations often show subtle growth features; a perfectly flat, mirror-like surface without any micro-texture may warrant closer scrutiny.

• Treatments: Color enhancements (heat/irradiation) are primarily issues in cut stones, not specimens. Oiling/fracture filling is unusual for jeremejevite crystals and should be disclosed if present. In practice, most specimen-quality jeremejevite is untreated.

Care and Storage

Jeremejevite is relatively hard (about 7–7.5 Mohs) but brittle, with a tendency to fracture from shock. Treat it like a delicate gem crystal.

• Handling: Support specimens with two hands and avoid pressure on slender tips. Use soft padding and secure mounts or mineral tack in display cases. Do not “test” for looseness by wiggling crystals—this can cause damage.

• Light and Temperature: Natural color is generally stable under normal display lighting. Avoid prolonged direct sun or high heat; rapid temperature swings can induce cracks. LED case lighting is ideal.

• Cleaning: Dust gently with a soft brush or air bulb. If needed, wash in lukewarm water with a drop of mild soap; rinse and air-dry fully. Avoid ultrasonic or steam cleaners and avoid strong acids/bases that could attack associated matrix minerals.

• Storage: Individually pad specimens to prevent contact with harder pieces. Keep away from vibration or shelf edges. Label clearly—provenance (e.g., Ameib Farm 60 or Davib Ost Farm 61) adds significant value on this rare species.

By focusing on pristine terminations, high clarity, and elegant composition—especially on contrasting matrix—collectors can secure a fine example of one of the mineral world’s most refined and elusive pegmatite gems.