From Your First Specimen
to a Museum-Grade Collection

Needle-like crystals, long and very thin — think of natrolite, rutile or millerite sprays. Fragile; handle by the matrix only.

The soft, floating bluish sheen of moonstone, caused by light scattering between microscopic layers inside the feldspar.

Minerals formed in Alpine clefts: quartz, adularia, fluorite, titanite, epidote and the classic "Alpine" species. Refers to the geological process, so it applies to the Alps and to similar settings worldwide.

A star-shaped reflection seen on some cabochon-cut stones — star sapphire, star ruby, star garnet — produced by oriented needle inclusions.

A rounded, grape-like surface formed by radiating crystals growing outward from many centres. Characteristic of malachite, hematite, chrysocolla and smithsonite.

The "cat's eye" effect: a single band of light that moves across the surface, caused by parallel fibrous inclusions or structure. Tiger's eye is the classic example.

An open crack in rock, lined with crystals that grew from circulating fluids. Alpine clefts are the classic source of crystal-clear quartz and adularia — and the goal of the Strahler.

Several crystals grown together as a single intergrown group, as opposed to one isolated crystal.

A specimen where two or more well-crystallized species share the matrix in an attractive arrangement. Valued above the sum of its parts when the contrast is strong.

The area where a specimen was joined to surrounding rock or another crystal before removal. A natural feature, but one that should always be disclosed.

Branching, tree- or fern-like growth, usually of manganese oxides on a rock surface or of native copper and silver. Often mistaken for fossil plants.

Small, brilliant, doubly terminated quartz crystals of the Herkimer type, found in several localities worldwide. Gem-like sparkle in a floater form.

A crystal with natural terminations at both ends, meaning it grew without being attached to a surface. Typically more desirable than a single-terminated crystal of the same species.

A carpet of tiny crystals covering a surface, often lining a cavity. Adds sparkle and texture rather than individual crystal definition.

A crust of one mineral that formed over another, which later dissolved away — leaving a hollow shell preserving the original crystal's outline.

A crystal whose faces were partly dissolved by later fluids, leaving pits, grooves or a frosted texture. Natural, and sometimes very beautiful — but always disclosed.

A specimen that previously belonged to a documented, usually notable, collection. Provenance of this kind adds both historical interest and value.

A shallow tray of specimens sold together, usually wholesale. A "flat" is how dealers buy at shows; single pieces are picked from it.

A specimen crystallized freely in a cavity or soft medium, with no point of attachment anywhere on its surface. Complete on all sides.

Visible light emitted by a mineral while it is illuminated by ultraviolet light. Response varies by wavelength: longwave 365 nm, midwave 302 nm, shortwave 254 nm.

Transparent and clear enough that the crystal could, in principle, be cut as a gemstone. A significant value factor in species like tourmaline, beryl and fluorite.

A rock cavity lined internally with crystals. Unremarkable outside, crystal-lined within.

The characteristic external shape a mineral tends to take: cubic, octahedral, prismatic, tabular, acicular, botryoidal, massive. A primary identification clue.

Collector shorthand for extremely fine, hair-like crystals — filiform millerite, byssolite or rutile. Spectacular under magnification, almost impossible to clean.

Doubly terminated, water-clear quartz crystals from Herkimer County, New York. The name is used loosely for similar crystals from elsewhere — check the locality.

A skeletal growth where the edges of the crystal grew faster than its faces, leaving recessed, stepped, window-like hollows. Classic in halite, bismuth and some quartz.

Formed from hot, mineral-rich water moving through rock. Most vein and cleft minerals — quartz, fluorite, baryte, sulfides — are hydrothermal.

Another mineral, a fluid or a gas trapped inside a crystal as it grew — rutile needles in quartz, chlorite phantoms, water bubbles (enhydro). Often adds value rather than removing it.

A rainbow-like play of colours on the surface, from a thin film or oxidation layer — iridescent hematite, chalcopyrite, "rainbow" pyrite. Fragile and easily rubbed off.

A group of specimens sold as one item, often for study, resale or for starting a collection. At ITALMINERAL, lots are tagged "Mineral Lot" in the shop.

How a surface reflects light: vitreous (glassy), adamantine (brilliant), metallic, resinous, silky, earthy. Independent of colour, and often more important to a specimen's impact.

A mineral occurring as a compact mass with no visible crystal faces. Judged on colour, texture and polish rather than crystal form.

ITALMINERAL's own top tier: a specimen that combines aesthetics, crystal quality, condition, rarity and locality at the highest level we handle. Few pieces earn the label.

The host rock on which crystals grew. "On matrix" indicates the specimen retains its natural geological context.

A small gas pocket in granite or pegmatite where crystals grew freely into open space. Source of many fine topaz, beryl and smoky quartz crystals.

An underground or open-pit working for ore. Many classic specimens come from mines that are now closed or flooded, which fixes the supply forever.

A relative scratch-resistance scale from talc (1) to diamond (10). Practical meaning: anything below 5 scratches easily against other specimens in storage.

Material from a recent discovery, before the market has established price levels. Prices can move sharply in either direction as the extent of the find becomes clear.

Material mined years or decades ago and held since, often from localities no longer producing. Frequently better prepared and documented than current production.

The sequence in which minerals formed on a specimen — which grew first, which came later. Reading it explains why one crystal sits on another.

A crystal that kept its external shape while its internal crystal structure changed to a different form of the same chemical composition — for example aragonite converted to calcite.

A very coarse-grained igneous rock, often with pockets, that produces large crystals of tourmaline, beryl, spodumene, topaz and rare-element species.

A ghost outline visible inside a transparent crystal, marking an interruption in growth where a thin layer of another mineral settled before growth resumed.

Light emission that continues after the UV source is switched off — from a fraction of a second to several minutes, depending on the species.

The shifting patches of spectral colour seen in precious opal, produced by diffraction from a regular array of silica spheres.

A crystal showing different colours when viewed along different crystallographic directions. Kunzite is a classic example, appearing pink, violet or near-colourless depending on the angle.

A natural cavity in rock where crystals grew into open space. A "pocket" in dealer language usually means a single find, and specimens from the same pocket share a family look.

An elongated crystal habit with parallel faces, like a pencil: tourmaline, beryl, quartz. The termination style is usually the identifying detail.

The documented history of a specimen: where it was collected, who owned it, which labels travelled with it. Provenance is proof, and proof is value.

One mineral that has replaced another while preserving the original's external crystal shape. Written as "A after B" — for example hematite after magnetite.

An open working for building stone, marble or aggregate. Quarries are accidental mineral producers — many Italian classics (Carrara, Baveno, Val Bregaglia) are quarry finds.

Spontaneous emission from unstable elements, principally uranium and thorium in mineral specimens. Measured in µSv/h and safely managed with sealed storage and sensible placement.

Repaired means broken pieces reattached. Restored means missing material has been added or reconstructed. Both are acceptable when disclosed; neither should ever be hidden.

A crystal with a wider, larger crystal grown over the tip of a narrower stem, resembling a royal sceptre. Common in quartz and amethyst.

A specimen the seller found personally in the field. Adds certainty about the locality and often a story worth keeping with the label.

A specimen that sits stably in its best display orientation without a stand. A practical, and surprisingly desirable, property in larger pieces.

A rock formed where hot magma reacted with limestone. A rich environment for garnet, vesuvianite, epidote, magnetite and hedenbergite crystals.

Growth where edges and corners developed faster than the faces, producing an open, hollowed or stepped framework rather than solid faces.

Treated with a consolidant so that a fragile or crumbly specimen holds together. Common for some fossils and porous minerals; always stated in our listings.

Formed as hanging, icicle-like growths — common in malachite, goethite and aragonite. A cut and polished cross-section shows concentric banding.

A collection organized to represent as many distinct mineral species as possible, arranged by chemical classification rather than by appearance.

Flat, plate-like crystals, wider than they are thick — baryte, wulfenite and many feldspars. Thin tabular crystals are easily chipped at the edges.

A reversible colour change: some hackmanite and sodalite darken under UV and fade again in daylight. A rare and fascinating property.

A collection built around geography — a region, a country or a single mine — rather than around species. Provenance documentation is central to it.

Flashes of light produced when a crystal is struck, rubbed or crushed — seen in some sphalerite, fluorite and quartz. Not something to test on a good specimen.

Excess matrix removed with a saw or trimmer to improve proportions. Standard practice, and the cut surfaces are normally kept out of the display view.

Two or more crystals of the same species intergrown in a specific, symmetrical orientation defined by the crystal structure — not a random intersection.

The place where a mineral species was first discovered and formally described. Specimens from a type locality carry particular scientific and collector significance.

Buying in quantity at a reduced per-piece price, typically by flat or lot. ITALMINERAL supplies dealers and resellers on request.