Fine mineral glossary.

Specimen

A natural mineral sample kept for its crystal form, colour or scientific interest rather than cut into a gemstone. A fine mineral specimen is one selected for exceptional quality.

Matrix

The host rock a crystal grew on or in. A specimen 'on matrix' keeps its natural base, which collectors often prize over a loose, detached crystal.

Termination

The natural crystal end-face where growth finished. A complete, undamaged termination is a key quality marker; a 'doubly terminated' crystal is finished at both ends.

Habit

The characteristic shape a mineral tends to grow in — cubic, prismatic, botryoidal, bladed, and so on. Habit helps identify a species and judge a specimen's appeal.

Crystal system

The symmetry class of a crystal's internal structure: cubic, tetragonal, hexagonal, trigonal, orthorhombic, monoclinic or triclinic. Each species belongs to one system.

Mohs hardness

A 1–10 scratch-resistance scale (talc = 1, diamond = 10). Quartz is 7; fluorite is 4. It guides how carefully a specimen must be handled and displayed.

Lustre

How a mineral's surface reflects light — vitreous (glassy), metallic, resinous, pearly, adamantine. Bright, clean lustre is part of a specimen's value.

Locality

The specific place a specimen was mined — ideally to mine level (e.g. Yaogangxian Mine, Hunan), not just a country. Locality is central to provenance and value.

Provenance

The documented origin and ownership history of a specimen. Verified provenance distinguishes a fine specimen from an anonymous piece and protects long-term value.

Type locality

The locality where a mineral species was first described and officially recognised. Specimens from a type locality carry special scientific and collector interest.

Druzy

A surface carpet of many tiny, sparkling crystals coating a matrix or larger crystal — for example, a druzy quartz coating.

Botryoidal

A rounded, grape-like surface formed by radiating crystal growth, classically seen in malachite and hematite.

Phantom

A ghost-like earlier crystal outline visible inside a larger transparent crystal, recording a pause in growth. Often seen in quartz.

Inclusion

Another mineral, fluid or gas trapped inside a host crystal as it grew. Inclusions can lower clarity or, when attractive, raise interest.

Twinning

Two or more crystals of the same species grown together in a symmetric, rule-governed way (e.g. the iron-cross twin in pyrite).

Cleavage

The tendency of a mineral to break along flat planes of structural weakness. Strong cleavage (as in fluorite or calcite) makes a specimen easier to damage.

Thumbnail

A size class: a specimen up to about 2.5 cm, traditionally displayed in a small box. Thumbnails are space-efficient and often very affordable.

Miniature

A size class roughly 2.5–5 cm — small enough to collect in numbers, large enough to show crystal detail.

Cabinet specimen

A larger display size, roughly 5–12 cm or more, meant to be shown openly on a shelf or in a cabinet as a statement piece.

Repair / restoration

Re-joining broken crystals or rebuilding lost areas. Reputable dealers disclose any repair; undisclosed repair is a serious quality and trust issue.

Treatment

Any human alteration of a natural specimen — heating, dyeing, irradiation, stabilising. Ethical practice requires full disclosure; 'untreated' means none was applied.

Grade

A quality tier assigned to a specimen. At Olemina the tiers are Fine Specimen, Premium and Exhibition, reflecting crystal quality, damage, colour and rarity.

Locality benchmark

A locality whose finest output defines the standard for a species — e.g. Sweet Home Mine for red rhodochrosite, or Yaogangxian for colour-zoned fluorite.

Putting it into practice? Browse the collection or read what makes a fine mineral specimen.