GemspringsShop on Etsy

Mineralpedia · open reference

A free reference encyclopedia of crystals and minerals.

Written by collectors for collectors. 27 species published so far — chemistry, formation, identification, market value and meaning. Every photo sourced from Wikimedia Commons under open licenses, with full attribution.

27 entriesCC-licensed photosUpdated continuously
Families:OxidesSulfidesSulfatesSilicatesCarbonatesHalidesOther
Showing 1–24 of 27 · page 1 of 2
Amethyst mineral specimen — Rock crystal and amethyst, likely from Rio Grande do Sul, Brazil. Exhibition “Stones and Reveries: TMohs 7

Amethyst

SiO₂ · Silicates

Amethyst is the purple variety of quartz, colored by iron impurities and natural irradiation. Mohs 7, vitreous luster, found in geodes worldwide — especially Uruguay and Brazil.

Aquamarine crystal mineral specimen — Aquamarine (Be₃Al₂(SiO₃)₆ or (Be₃Al₂Si₆O₁₈) is a variety of the beryl family and ranges from a pale Mohs 7.75

Aquamarine

Be₃Al₂Si₆O₁₈ (+ Fe trace) · Silicates

Aquamarine is the iron-coloured blue variety of beryl (same species as emerald). Mohs 7.5–8, hexagonal prisms. Brazilian 'Santa Maria' is the deep-blue benchmark.

Carnelian chalcedony stone mineral specimen — Minerals in a box in the “Kakteenland Steinfeld” Object: Mineral Title Mineral Part of rock Object: Mohs 7

Carnelian

SiO₂ (chalcedony) · Silicates

Carnelian is the orange to red translucent variety of chalcedony, coloured by iron oxide. Mohs 7. One of the oldest used gemstones — found in Sumerian and Egyptian tombs from 3000 BCE.

Citrine crystal mineral specimen — quartz var. amethyst, quartz var. citrine : Karibib District, Erongo Region, NamibiaMohs 7

Citrine

SiO₂ · Silicates

Citrine is the yellow to brown variety of quartz, coloured by aluminium impurities and natural radiation. Most commercial citrine is heat-treated amethyst from Brazil.

Emerald crystal mineral specimen — Blue topaz crystals from Brazil.Mohs 7.75

Emerald

Be₃Al₂Si₆O₁₈ (+ Cr/V trace) · Silicates

Emerald is the chromium- or vanadium-coloured green variety of beryl. Mohs 7.5–8, Colombia produces the world's reference gem; Zambia and Brazil dominate supply.

Fluorite mineral specimen — Green fluorite twinned crystals up to 18 mm in size on matrix (5.4 × 5 × 3.7 cm). Found from Diana MMohs 4

Fluorite

CaF₂ · Halides

Fluorite (CaF₂) is calcium fluoride — defines Mohs 4 on the hardness scale. Famous for cubic crystals in every colour of the rainbow and for fluorescence under UV light.

Kunzite crystal mineral specimen — crystal of spodumene var. kunzite : Laghman Province (Lagman Province ; Nuristan), AfghanistanMohs 6.75

Kunzite

LiAl(SiO₃)₂ · Silicates

Kunzite is the pink lithium-bearing variety of spodumene, discovered in 1902. Mohs 6.5–7, strong pleochroism. Mawi (Afghanistan) and Pala (California) are the historic top sources.

Labradorite mineral specimen — Anorthosite from the Precambrian of Finland. Anorthosite is a coarsely-crystalline, intrusive igneouMohs 6.25

Labradorite

(Ca,Na)(Al,Si)₄O₈ · Silicates

Labradorite is a plagioclase feldspar showing 'labradorescence' — vivid iridescent flashes of blue/green/gold/violet. Discovered 1770 Labrador; Finnish 'Spectrolite' is the most spectacular variety.

Lapis lazuli mineral specimen — Figures 1-7. The Topaz. 1. Topaz 2. The same [Topaz] 3. Dark Yellow Topaz 4. Sea-green Topaz or AquaMohs 5.5

Lapis Lazuli

(Na,Ca)₈(AlSiO₄)₆(SO₄,S,Cl)₂ (mainly lazurite) · Silicates

Lapis lazuli is a deep blue metamorphic rock dominated by lazurite, with pyrite flecks and calcite veins. Mined for 7,000 years; Afghanistan's Sar-i-Sang is the historic and finest source.

Malachite mineral specimen — Dark green malachite in a botryoidal habit, the crystal part of the specimen is approximately 5 cm aMohs 3.75

Malachite

Cu₂CO₃(OH)₂ · Carbonates

Malachite is a vivid green copper carbonate mineral (Cu₂CO₃(OH)₂) famous for concentric banded structure. Mohs 3.5–4 (soft). DRC produces 90%+ of commercial display material.

Moonstone mineral adularescence mineral specimen — Adularia (Moonstone)- Adularia showing adularescence - Deposit topotype - Adula Mts, Ticino (Tessin)Mohs 6.25

Moonstone

(K,Na)AlSi₃O₈ · Silicates

Moonstone is the gem variety of orthoclase feldspar showing 'adularescence' — a billowing blue or rainbow sheen caused by light scattering off layered structure. Sri Lanka produces the finest blue.

Morganite crystal mineral specimen — beryl var. morganite : Chamachhu Pegmatites, Chamachhu, Haramosh Mounts, Skardu District, Baltistan,Mohs 7.75

Morganite

Be₃Al₂Si₆O₁₈ (+ Mn trace) · Silicates

Morganite is the manganese-coloured pink to peach variety of beryl, same species as emerald and aquamarine. Mohs 7.5–8, named for J.P. Morgan in 1911 by gemmologist George Kunz.

Obsidian mineral specimen — (crack surface) Obsidian is a glassy-textured, extrusive igneous rock. Obsidian is natural glass - iMohs 5.5

Obsidian

SiO₂ (amorphous, with minor Mg, Fe, Na, K) · Other

Obsidian is naturally occurring volcanic glass — rapidly cooled rhyolitic lava that lacks crystal structure. Mohs 5.5, conchoidal fracture. Used by humans for tools 700,000+ years.

Opal mineral specimen — Figures 1-20. Quartz and Opal. 1. Grey and White Striped Flint 2. Carnelian 3. Fortification Agate 4Mohs 5.5

Opal

SiO₂·nH₂O · Silicates

Opal is hydrated silica (SiO₂·nH₂O) — not a true crystal but a mineraloid. Famous for "play-of-colour" diffraction. Australia produces ~95% of precious opal worldwide.

Peridot crystal mineral specimen — Peridotite mantle xenoliths in vesicular phonotephrite from the Pleistocene of Arizona, USA. Green =Mohs 6.75

Peridot

(Mg,Fe)₂SiO₄ · Silicates

Peridot is the gem variety of the magnesium-iron silicate olivine. Mohs 6.5–7, signature yellow-green colour from iron. Mined for 3,500 years; Egypt's Zabargad is the original source.

Pyrite mineral specimen — Cubic crystals of pyrite (7.0 × 5.0 × 2.5 cm). Found from Huanzala mine, Huallanca, Bolognesi, AncasMohs 6.5

Pyrite

FeS₂ · Sulfides

Pyrite (FeS₂) is iron sulfide — "fool's gold". Forms striking metallic-gold cubes and pyritohedrons. Mohs 6.5, density 5.0, brass-yellow streak greenish-black.

Quartz crystal mineral specimen — Crystals of tetrahedrite up to 2.2 cm in size forming a cluster (3.5 × 2.5 × 2.5 cm) with quartz andMohs 7

Quartz

SiO₂ · Silicates

Quartz (SiO₂) is the second most abundant mineral in Earth's crust. Trigonal silicate, Mohs 7, vitreous luster — base of amethyst, citrine, rose quartz, and dozens of varieties.

Rhodochrosite mineral specimen — Rhodochrosite in different crystallization variants. Exhibited at the Royal Ontario Museum From leftMohs 3.75

Rhodochrosite

MnCO₃ · Carbonates

Rhodochrosite (MnCO₃) is a manganese carbonate, raspberry-red, very soft (Mohs 3.75). The Sweet Home Mine in Colorado produced the world's finest crystals.

Rose quartz mineral specimen — crystals of eosphorite, crystals of rose quartz : Ilha claim, Taquaral, Itinga, Jequitinhonha ValleyMohs 7

Rose Quartz

SiO₂ · Silicates

Rose quartz is the pink translucent variety of quartz, coloured by dumortierite microfibers. Mohs 7, almost always massive (no faceted crystals). Brazil and Madagascar dominate supply.

Ruby gemstone mineral specimen — Corundum, Al2O3, comes in many colors. Sometimes it is gemmy and has value as a gemstone (ruby or saMohs 9

Ruby

Al₂O₃ (+ Cr trace) · Oxides

Ruby is the chromium-red variety of corundum (Al₂O₃). Mohs 9, second hardest natural mineral. Burma's Mogok produces the legendary 'pigeon-blood' colour benchmark.

Selenite mineral specimen — Gypsum var. Selenite Crystal Cluster from Sandoval County, New MexicoMohs 2

Selenite

CaSO₄·2H₂O · Sulfates

Selenite is the transparent crystalline variety of gypsum (CaSO₄·2H₂O). Mohs 2 — very soft. Famous for the giant 12-meter crystals of Naica, Mexico.

Smoky quartz mineral specimen — cristaux de microcline var. amazonite et cristaux de quartz fuméMohs 7

Smoky Quartz

SiO₂ · Silicates

Smoky quartz is the brown-to-black variety of quartz, coloured by natural radiation acting on aluminium impurities. Mohs 7, often forms large terminated crystals.

Spinel gemstone mineral specimen — Spherical concentration of crystals in a gem spinelMohs 8

Spinel

MgAl₂O₄ · Oxides

Spinel is a magnesium aluminate, often confused with ruby for centuries (the 'Black Prince's Ruby' is actually spinel). Mohs 8, cubic, singly refractive. Burma's Mogok produces top red.

Tanzanite mineral specimen — Zoisite Locality: Merelani Hills (Mererani), Lelatema Mts, Arusha Region, Tanzania (Locality at mindMohs 6.5

Tanzanite

Ca₂Al₃(SiO₄)(Si₂O₇)O(OH) · Silicates

Tanzanite is the violet-blue variety of zoisite, found ONLY at Merelani in northern Tanzania. Mohs 6.5, strong pleochroism. One of the rarest gemstones — single mine source on Earth.