Weeksite is a naturally occurring

uranium Uranium is a chemical element with the symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium is weak ...

silicate mineral with the chemical formula: K₂(UO₂)₂Si₆O₁₅•4(H₂O), potassium uranyl silicate. Weeksite has a

Mohs hardness The Mohs scale of mineral hardness () is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. The scale was introduced in 1812 by th ...

of 1–2. It was named for

USGS The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, a ...

mineralogist Alice Mary Dowse Weeks (1909–1988).

Appearance

Weeksite is visually similar to other uranium minerals such as carnotite and

zippeite Zippeite is a hydrous potassium uranium sulfate mineral with formula: K4( U O2)6( SO4)3(O H)10·4( H2O). It forms yellow to reddish brown monoclinic-prismatic crystals with perfect cleavage. The typical form is as encrustations and pulverulent ear ...

, both being encrustations that form on other rocks (usually

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) ...

s or

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

s).

Occurrence

Weeksite was first described in 1960 for an occurrence on

Topaz Mountain Topaz Mountain is a summit in the Thomas Range of Utah, east of the Thomas caldera. The summit and surrounding area are known for their abundances of semiprecious minerals including topaz, red beryl and opal. Geology and geography Topaz Mountain ...

Thomas Range The Thomas Range is a mountain range of north central Juab County of western Utah, United States. Topaz Mountain is in the southern part of the range and Spor Mountain lies to the southwest.''Utah Atlas & Gazeteer,'' DeLorme, 9th ed., 2014, pp. ...

, Juab County, Utah. Weeksite occurs within small "opal"

veins Veins are blood vessels in humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated b ...

within

rhyolite Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained groundmass. The mineral ...

and

agglomerate Agglomerate (from the Latin ''agglomerare'' meaning "to form into a ball") is a coarse accumulation of large blocks of volcanic material that contains at least 75% bombs. Volcanic bombs differ from volcanic blocks in that their shape records flui ...

s, and as encrustations in sandstones and limestones. It occurs associated with

opal Opal is a hydrated amorphous form of silica (SiO2·''n''H2O); its water content may range from 3 to 21% by weight, but is usually between 6 and 10%. Due to its amorphous property, it is classified as a mineraloid, unlike crystalline forms ...

, chalcedony,

calcite Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...

gypsum Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula . It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, blackboard or sidewalk chalk, and drywall. ...

, fluorite,

uraninite Uraninite, formerly pitchblende, is a radioactive, uranium-rich mineral and ore with a chemical composition that is largely UO2 but because of oxidation typically contains variable proportions of U3O8. Radioactive decay of the uranium causes t ...

, thorogummite, uranophane, boltwoodite, carnotite and

margaritasite Margaritasite is a yellow, caesium-bearing mineral in the carnotite group. Its chemical formula is ( Cs, K, H3O)2( U O2)2 V2O8· H2O and its crystal system is monoclinic (space group ''P21/a''). Name and discovery It was first described in 1982 ...

References

Uranium(VI) minerals Potassium minerals Nesosilicates Orthorhombic minerals Minerals in space group 52 {{Silicate-mineral-stub

Appearance

Occurrence

See also

References