sunstones
plural of sunstone

sussexite
A monoclinic manganese borate mineral with the chemical formula MnBO₂(OH).

sussexites
plural of sussexite

svanbergite
A rhombohedral mineral with the chemical formula SrAl₃(PO₄)(SO₄)(OH)₆.

svetlozarite
A zeolite containing calcium, potassium, sodium, aluminium, silicon, hydrogen and oxygen.

symesite
A triclinic-pinacoidal pink mineral with the chemical formula Pb₁₀(SO₄)O₇Cl₄ · H₂O.

szmikite
A soft monoclinic mineral with the chemical formula MnSO₄·(H₂O).

szmikites
plural of szmikite

talc
Originally a large range of transparent or glistening foliated minerals. Examples include mica, selenite and the hydrated magnesium silicate that the term talc generally has referred to in modern times (see below). Also an item made of such a mineral and depending for its function on the special nature of the mineral (see next). Medieval writers adopted the term from the Arabic.
A microscope slide made of a plate of mica, generally in use from the start of modern microscopy until the early nineteenth century, after which glass slides became the standard medium.
A soft mineral, composed of hydrated magnesium silicate, that has a soapy feel and a greenish, whitish, or grayish color, and usually occurs in foliated masses.
Talcum powder.

talcs
plural of talc

tawmawite
A chromium-bearing variety of epidote.

tectosilicate
Any of various silicate minerals, mostly aluminosilicates, with a three-dimensional framework of silicate tetrahedra with SiO₂ or a 1:2 ratio, making up the greater part of Earth's crust.

tectosilicates
plural of tectosilicate

tektosilicate
Alternative spelling of tectosilicate.

tektosilicates
plural of tektosilicate

temagamite
An orthorhombic gray mineral containing mercury, palladium, and tellurium with chemical formula Pd₃HgTe₃.

tetraoxosilicate
Synonym of orthosilicate.

tetraoxosilicates
plural of tetraoxosilicate

thorite
A radioactive mineral, composed mostly of thorium silicate (ThSiO₄), along with silicates of uranium and the rare earths.

thorites
plural of thorite

thortveitite
A scandium yttrium silicate mineral, greyish-green, black or grey in colour, the primary source of scandium.

thortveitites
plural of thortveitite

thuringite
A hydrous silicate of iron and aluminium occurring as an aggregation of minute olive-green scales

thuringites
plural of thuringite

tiemannite
An isometric-hextetrahedral grayish white mineral containing mercury and selenium; mercury selenide, chemical formula HgSe.

tiemannites
plural of tiemannite

tiemmannite
Misspelling of tiemannite.

tirodite
A mineral with chemical formula Mn₂Mg₅Si₈O₂₂(OH)₂.

titanite
A mixed calcium and titanium neosilicate, CaTiSiO₅, once known as sphene.

toepass
Alternative form of topaz (“black Catholic soldier in the British Army”).

toepasses
plural of toepass

topass
Alternative form of topaz (“black Catholic soldier in the British Army”).

topaz
A silicate mineral of aluminium and fluorine, usually tinted by impurities.
An often clear, yellowish-brown gemstone cut from this.
A yellowish-brown color, like that of the gemstone.
Or (gold or yellow), in blazoning by precious stones.
Either of two species of very large hummingbirds in the genus Topaza.
A ruby-topaz hummingbird, Chrysolampis mosquitus, the male of which has bright ruby feathers on the head and topaz on the throat

topazes
plural of topaz

tounkite
A hexagonal-trapezohedral mineral with the chemical formula (Na,Ca,K)₈(Al₆Si₆O₂₄)(SO₄)₂Cl · H₂O.

toupas
Alternative form of topaz (“black Catholic soldier in the British Army”).

toupases
plural of toupas

tourmalin
Alternative form of tourmaline.

tourmaline
A complex black or dark-coloured borosilicate mineral, compounded with various chemical elements and considered a semi-precious stone.
A transparent gemstone cut from it.

tourmalines
plural of tourmaline

tourmalins
plural of tourmalin

trachyphonolite
trachytic phonolite

trachyphonolites
plural of trachyphonolite

tremolite
A pale grey/green amphibole mineral, a type of asbestos, that is a mixed calcium and magnesium silicate, with the chemical formula Ca₂Mg₅Si₈O₂₂(OH)₂; sometimes used in place of common asbestos.

tremolites
plural of tremolite

trowlesworthite
A mineral from the west of England, consisting of red felspar, black tourmaline, and purple fluor.

tsingtauite
A porphyritic granite with phenocrysts of orthoclase in a fine-grained groundmass of quartz and alkali feldspar having an evenly granular fabric.

tugtupite
A rare beryllium-aluminium tectosilicate with a structure similar to that of sodalite.

tugtupites
plural of tugtupite

turmaline
Alternative form of tourmaline.

turmalines
plural of turmaline

uchucchacuaite
A mineral with the chemical formula (AgMnPb₃Sb₅S₁₂), often found in hydrothermal deposits.

uklonskovite
A monoclinic mineral with a vitreous lustre that has the chemical formula NaMg(SO₄)F.

umbalite
A variety of garnet consisting of a mixture of pyrope, almandine, and spessartine, having the chemical formula Mg₃Al₂(SiO₄)₃-Mn²⁺₃Al₂(SiO₄)₃, exclusively found in the alluvial deposits of the River Umba, and having a light-pink to purple colour.
A gemstone consisting of the mineral umbalite.

umbalites
plural of umbalite

umbite
An inosilicate mineral of potassium, zirconium and titanium

umboldilite
Alternative form of humboldtilite.

unakite
An altered granite composed of pink orthoclase feldspar, green epidote, and generally colorless quartz.

unakites
plural of unakite

uncompahgrite
A coarse-grained melilitic rock containing more than 10% pyroxene.

uncompahgrites
plural of uncompahgrite

uranophane
A rare yellow radioactive calcium uranium silicate hydrate mineral that forms from the oxidation of uranium-bearing minerals.

uranophanes
plural of uranophane

urtite
A mineral consisting largely of nepheline, with aegirine and apatite, but no feldspar.

ussingite
A white or reddish-pink silicate mineral with chemical formula Na₂AlSi₃O₈(OH).

valbellite
A variety of peridotite with bronzite, olivine, hornblende, etc.

valencianite
A feldspar mineral, a variety of adularia.

vallevarite
A form of anorthosite, chemically similar to monzonite or mangerite.

varnsingite
A coarse-grained whitish igneous dyke rock consisting of albite, pyroxene, titanite, magnetite and apatite with secondary epidote, prehnite and muscovite.

venanzite
An olivine melilitite mineral from San Venanzo in Italy.

vermiculite
A hydrated silicate mineral which expands on heating; it is used in insulation and as a medium for planting.

vermiculites
plural of vermiculite

vesbite
A lava composed of about 65% leucite, 18% humboldtilite, 20% pyroxene, and 2% magnetite.

vesbites
plural of vesbite

vessonite
Alternative form of vesuvianite.

vessonites
plural of vessonite

vesuvianite
A yellow, green or brown mineral, a mixed calcium, magnesium and aluminium silicate sometimes used as a gemstone.

vesuvianites
plural of vesuvianite

villemite
Alternative form of willemite.

vlodavetsite
A tetragonal-dipyramidal mineral with the chemical formula AlCa₂(SO₄)₂F₂Cl · 4H₂O.

vrbaite
An opaque, brittle mineral with chemical formula Tl₄Hg₃Sb₂As₈S₂₀.

vyuntspakhkite
A mineral comprising mostly aluminosilicates of yttrium, ytterbium and various lanthanides

wadalite
A vitreous nesosilicate of calcium, aluminium and magnesium

wadsleyite
An orthorhombic form of olivine produced under very high pressure

wadsleyites
plural of wadsleyite

wehrlite
A type of peridotite that is a mixture of olivine and clinopyroxene.
A naturally-occurring alloy of bismuth and tellurium, primarily Bi₂Te₃.

wehrlites
plural of wehrlite

weinbergerite
A silicate intermediate in chemical composition to pyroxene and nepheline.

weiselbergite
A deep black and light blue magmatic rock with isolated pieces of feldspar.

weiselbergites
plural of weiselbergite

welinite
A red trigonal mineral which is a manganese, tungsten silicate.