willemseite
A monoclinic-prismatic light green mineral containing hydrogen, magnesium, nickel, oxygen, and silicon.

willhendersonite
A triclinic-pinacoidal colorless mineral containing aluminum, calcium, hydrogen, oxygen, potassium, and silicon.

williamsite
A translucent green variety of antigorite sometimes used as a gem.

williamsites
plural of williamsite

willyamite
An isometric-tetartoidal mineral containing antimony, cobalt, nickel, and sulfur.

wiltshireite
Synonym of rathite.

winchite
A monoclinic-prismatic mineral containing aluminum, calcium, hydrogen, iron, magnesium, manganese, oxygen, potassium, silicon, and sodium.

winstanleyite
An isometric-diploidal mineral containing oxygen, tellurium, and titanium.

winterbourne
A stream that only flows in winter or after wet weather, particularly in an area rich in limestone.

winterbournes
plural of winterbourne

wiserite
A tetragonal-dipyramidal mineral containing boron, chlorine, hydrogen, manganese, and oxygen.

wittichenite
An orthorhombic-disphenoidal mineral containing bismuth, copper, and sulfur.

wittingite
A form of neotocite from Norway

wittite
A monoclinic-prismatic light lead gray mineral containing bismuth, lead, selenium, and sulfur.

wocheinite
Synonym of bauxite.

wodginite
A brown to black mineral comprising mainly tantalum.

wodginites
plural of wodginite

wolchonskoite
Alternative form of volkonskoite.

wolfeite
A monoclinic-prismatic mineral containing hydrogen, iron, manganese, oxygen, and phosphorus.

wolfram
wolframite
tungsten

wolframite
A mineral that consists of a tungstate of iron and manganese; (Fe,Mn)WO₄; it is one of the principal ores for tungsten.

wolframites
plural of wolframite

wolfsbergite
chalcostibite; jamesonite

wolftonite
Synonym of hydrohetaerolite.

wolgidite
A diopside-leucite-richterite madupitic lamproite.

wonesite
A monoclinic-prismatic mineral containing aluminum, fluorine, hydrogen, iron, magnesium, oxygen, potassium, silicon, and sodium.

woodallite
A trigonal-hexagonal scalenohedral mineral containing aluminum, carbon, chlorine, chromium, hydrogen, iron, magnesium, and oxygen.

woodendite
A basaltic igneous rock found in Victoria, Australia.

woodhouseite
A trigonal-hexagonal scalenohedral mineral containing aluminum, calcium, hydrogen, oxygen, phosphorus, and sulfur.

woodrock
A compact wood-like variety of asbestos.

woodruffite
A tetragonal mineral containing hydrogen, manganese, oxygen, and zinc.

woodstone
A striped variety of hornfels, resembling wood in appearance.
petrified wood

woodstones
plural of woodstone

woodwardite
A hexagonal mineral containing aluminum, copper, hydrogen, oxygen, and sulfur.

wooldridgeite
An orthorhombic-pyramidal greenish blue mineral containing calcium, copper, hydrogen, oxygen, phosphorus, and sodium.

wroewolfeite
A monoclinic-domatic mineral containing copper, hydrogen, oxygen, and sulfur.

wulfenite
An orange mineral, lead molybdate, PbMoO₄, found in lead veins.

wulfenites
plural of wulfenite

wupatkiite
A monoclinic-prismatic mineral containing aluminum, cobalt, hydrogen, magnesium, nickel, oxygen, and sulfur.

wurtzilite
A black, insoluble, carbonaceous material formed from the metamorphosis of shale oil.

wurtzilites
plural of wurtzilite

wycheproofite
A triclinic-pinacoidal mineral containing aluminum, hydrogen, oxygen, phosphorus, sodium, and zirconium.

wyllieite
A monoclinic-prismatic mineral containing aluminum, calcium, iron, magnesium, manganese, oxygen, phosphorus, and sodium.

xalostocite
Synonym of rosolite.

xanthocone
Synonym of xanthoconite.

xanthoconite
A mineral containing silver, arsenic, and sulphur.

xanthophyllite
A synonym of clintonite. The International Mineralogical Association's Commission on New Minerals, Nomenclature and Classification (CNMNC) recommends using clintonite as a replacement in all cases.

xanthophyllites
plural of xanthophyllite

xanthosiderite
Synonym of limonite.

xanthosiderites
plural of xanthosiderite

xanthoxenite
A dull brown or yellow triclinic mineral.

xanthoxenites
plural of xanthoxenite

xenoblast
A crystal forming in a metamorphic rock that has not developed its characteristic crystalline faces and which gets its shape from bordering crystals.

xenoblasts
plural of xenoblast

xenocryst
An isolated crystal having a different origin than the igneous rock in which it is found; the mineralogical equivalent of a xenolith.

xenocrystal
Alternative form of xenocryst.

xenocrystals
plural of xenocrystal

xenocrysts
plural of xenocryst

xenolite
Xenolith.

xenolith
Any piece of rock having a different origin to that of the igneous rock in which it is found.

xenoliths
plural of xenolith

xenotite
A mineral that is a source of rare earth metals.

xiangjiangite
A yellow mineral composed of aluminium, hydrogen, iron, oxygen, phosphorus, sulphur, and uranium.

xifengite
A grey metallic hexagonal mineral.

xingzhongite
An opaque metallic mineral composed of copper, iridium, iron, lead, platinum, rhodium, and sulphur.

xingzhongites
plural of xingzhongite

xocomecatlite
A telluride mineral found in cracks in altered rhyolite.

xuwenyuanite
An isometric mineral.

xylochlore
An altered form of apophyllite.

xylotile
An altered form of asbestos.

xylotiles
plural of xylotile

yafsoanite
An isometric-hexoctahedral mineral containing calcium, oxygen, tellurium, and zinc.

yagiite
A hexagonal-dihexagonal dipyramidal colorless mineral containing aluminum, magnesium, oxygen, potassium, silicon, and sodium.

yakhontovite
A monoclinic-prismatic pistachio green mineral containing calcium, copper, hydrogen, iron, magnesium, oxygen, potassium, and silicon.

yamaskite
A form of pyroxenite.

yamaskites
plural of yamaskite

yanolite
axinite

yanomamite
An orthorhombic-dipyramidal mineral containing arsenic, hydrogen, indium, and oxygen.

yaroslavite
An orthorhombic white mineral containing aluminum, calcium, fluorine, hydrogen, and oxygen.

yarrowite
A trigonal-ditrigonal pyramidal mineral containing copper and sulfur.

yatalite
A form of coarse-grained pegmatite composed of uralitic actinolite.

yavapaiite
A monoclinic-prismatic light pink mineral containing iron, oxygen, potassium, and sulfur.

yeatmanite
A triclinic-pinacoidal clove brown mineral containing antimony, manganese, oxygen, silicon, and zinc.

yecoraite
A tetragonal mineral containing bismuth, hydrogen, iron, oxygen, and tellurium.

yedlinite
A trigonal-rhombohedral red violet mineral containing chlorine, chromium, hydrogen, lead, and oxygen.

yenerite
Synonym of boulangerite.

yenite
Alternative form of jenite.

yentnite
A supposed form of scapolite, later found to be quartz.

yeremeyevite
Alternative form of jeremejevite.

yftisite
A yellow mineral containing mostly yttrium, oxygen, and fluorine.

yimengite
A hexagonal-dihexagonal dipyramidal black mineral containing aluminum, barium, chromium, iron, magnesium, oxygen, potassium, silicon, and titanium.

yingjiangite
An orthorhombic-dipyramidal mineral containing calcium, hydrogen, oxygen, phosphorus, potassium, and uranium.

yixunite
An isometric-hexoctahedral bright white mineral containing indium and platinum.

yoderite
A monoclinic-sphenoidal mineral containing aluminum, hydrogen, iron, magnesium, manganese, oxygen, and silicon.

yofortierite
A monoclinic-domatic mineral containing aluminum, calcium, hydrogen, magnesium, manganese, oxygen, silicon, and zinc.

yogoite
monzonite

yoshimuraite
A triclinic-pinacoidal orange brown mineral containing barium, hydrogen, iron, manganese, oxygen, phosphorus, silicon, strontium, sulfur, and titanium.

yoshiokaite
A trigonal-rhombohedral mineral containing aluminum, calcium, oxygen, and silicon.

ytterite
gadolinite

yttrobetafite
A rare radioactive uranium-titanium-niobium mineral characterized by its yttrium content, often found in lunar rocks and rare Earth deposits, that belongs to the pyrochlore group.

yttrocolumbite
Yttrotantalite.

yttrofluorite
A form of fluorite that is rich in yttrium