Oxide Mineral Collection

Franklinite, zinc ore
A granular rock composed of white calcite, dull green willemite, red zincite and black franklinite (Zinc Iron Manganese Oxide). See T00387 for a fluorescent view

Perovskite
Large black, pseudocubic crystals of perovskite (calcium titanium oxide). It is a source of titanium and some rare earth metals

Crucifix set with sapphires, zircon, spinel, cairngorm and amethyst. The whole cross is bordered by diamonds

Corundum variety ruby; crystal and gems
Crystal and gem specimens of ruby, the red variety of the mineral corundum (aluminium oxide). Corundum has two varieties, the other being sapphire

Moon rock fragment from the last Apollo space mission, Apollo 17, encased in perspex on a wooden plaque. The thumbnail-size rock is around 3.7 billion years old

The Hope Chrysoberyl
Glittering 45-carat chrysoberyl gemstone from Brazil which, has been known among gemmologists for about 170 years

Sapphire Buddha pin less then two centimetres tall. Sapphie is so hard it would have needed something as hard or harder to shape it, most probably another Sapphire

Limonite, also known as ironstone, is comprised of (hydrated iron oxide) and is characterized by its rusty colour and banded appearance

Chrysoberyl cut stone
This is Alexandrite, a cushion-shaped Chrysoberyl (beryllium aluminum oxide) gemstone. Alexandrite is named after the former czar of Russia, Alexander II

Alexandrite crystals
A cluster of the gemstone alexandrite trillings, or twinned crystals. This gemstone was named after the Russian Tsar Alexander II. It can appear in both red or green

Diamond flower brooch
Victorian diamond-encrusted flower with a sapphire at its centre

Yellow sapphire from Sri Lanka, 101 carats. Acquired by the museum in 1874

Padparadscha is one of the most unusual varieties of the mineral corundum

Blue sapphire
Sri Lankan specimen of blue sapphire. A rare example of the uncut material

Spinel specimen
Spinel crystals from Vietnam. The rock has been chipped away to reveal the well-defined crystals

Diamond spikes

Natural ruby crystal
This ruby is a staggering 1, 085 carats. Mined in Burmas Mogok (Myanmar s) mines and bought by the Museum in 1924 from Burma Ruby Mines Ltd. It is one of the largest crystals in the Museum collection

Star sapphire
Parallel bundles of fibres are formed in the stone as it crystallises. When the sapphire is cut in the correct orientation the silky needles reflect light to form a star effect

Natural ruby in marble
From the mines of Mogok in Burma (Myanmar). Ruby is the red variety of the mineral corundum with small impurities of chromium that turn it red

Cursed amethyst
When the Mineralogy Department received this amethyst in 1943 they found a note inside the box: this stone is trebly accursed and is stained with the blood

Magnetite (iron oxide) specimen from Piedmont, Italy. From the collections of the Natural History Museum, London

Corundum group
A collection of crystals including ruby and sapphire particolor, ruby rhomboid, and hexagonal cut sapphire

Ruby and Sapphire
Specimens of the mineral corundum (Aluminum Oxide), a ruby and saphire. These gemstones are varieties of the corundum mineral. A collection of crystals including the Edwardes ruby

Sapphire turban button
A rose-cut facetted deep-blue sapphire mounted in a button of quartz, inlaid with gold, rubies & emeralds. No 198 in the collection of Sir Hans Sloane

Columbite
Specimen used by Charles Hatchett when he discovered niobium (then called columbium) and now called columbite in 1801. Mineral collection, the Natural History Museum

The discovery of Niobium
Paper by Charles Hatchett, read at the Royal Society London 1801, describing how he discovered niobium (then called columbium). This mineral is now known as Columbite

Psilomelane
A bright black botryoidal mass of psilomelane. Psilomelane comprises of (barium manganese oxide hydroxide). Specimen from Monkstone mine, Brent Tor, Devon

Pyrochlore
Scanning electron microscope images of elemental maps showing thorium, uranium, tantalum and silicon in the mineral pyrochlore from Sokli, Finland

Cassiterite
A dark-brown single crystal of cassiterite among quartz. Cassiterite comprises of (tin oxide) and forms ornately faceted crystals with high lustre. Specimen from Turnavore mine, St. Agnes, Cornwall

Cassiterite pseudomorphous after orthoclase
Brown granular cassiterite (tin oxide) have replaced twinned orthoclase crystals. Wheal Coates, St. Agnes, Cornwall

Manganite (manganese oxide hydroxide), characterized by short prismatic crystals. This specimen is held at the Natural History Museum, London

Realgar comprises of (arsenic sulphide). It is also known as ruby sulphur and is a rare non-metallic sulphide mineral. Specimen from the Natural History Museum, London

Sohngeite

Wood tin, variety of cassiterite
Dark-brown banded aggregates of cassiterite intergrown with white quartz and black tourmaline. Cassiterite comprises of (tin oxide). This polished specimen is from West Kitty mine, St. Agnes, Cornwall

Trechmannite
A red crystal of trechmannite comprised of (silver arsenic sulphide). A specimen from the collections of the Natural History Museum, London

Goethite comprises of hydrated iron oxide. Picture shows radiating bands within the disc-shaped crystals. This specimen is displayed at the Natural History Museum, London

Pleochroism in an iolite cut stone
This iolite (magnesium aluminium silicate) is displaying pleochroism, a varied colour effect as the gem is turned. See also 3960

Spinel crystal and cut stone
Spinel (magnesium aluminium oxide) crystal from Ruby Mines, Mogok, Burma with spinel cut stone from Sri Lanka. Spinel is found in a red colour and has been previously mistaken for ruby

Anatase
A brown to black single tetragonal crystal of anatase (titanium oxide). Anatase is a polymorph of rutile and brookite, meaning they carry the same chemistry, but with a different structure

Many colours of corundum
Ruby and sapphire cut corundum stones viewed through their pavilions. Corundum is the second hardest natural mineral known

Rubies and sapphires
Crystals of ruby from Burma which is the red variety of corundum (aluminium oxide). The other variety is sapphire, this specimen is from Kashmir. The lower left specimen is the Edwardes Ruby

Braunite is a native oxide of manganese. Its crystals are dark brownish black in colour. Specimen from the Natural History Museum, London

Ruby and sapphire gravel
Ruby and sapphire fragments from gem gravels seen on a background of slate. Ruby and sapphire are both varieties of the mineral corundum (aluminium oxide)

Tiger s-eye and Hawk s-eye
Formed when blue crocidolite asbestos is replaced by quartz. Hawk s-eye retains the original colour while tiger s-eye contains a residue of iron oxide

Zincite comprises of (zinc oxide). It is an important ore of zinc, and almost exclusive to one mining locality in New Jersey, U.S.A. Specimen from the Natural History Museum, London

Tenorite is comprised of (copper oxide). It is found as grey to black metallic crystals and as a by-product of lava flows. Fibrous specimen from the Natural History Museum, London

Franklinite, fluorescing
Ore of zinc fluorescing under ultra violet radiation: calcite - pink; willemite - green; zincite - blue; franklinite - black. See image number 388 for white light view

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