weeksite

{{infobox mineral | name = Weeksite | boxwidth = | image = Weeksita-RM1439.jpg | alt = | caption = | category = Silicate mineral | formula = K2(UO2)2Si6O15·4(H2O) | IMAsymbol = Wks | molweight = | strunz = 9.AK.30 | dana = | system = Orthorhombic | class = Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m) | symmetry = Pnnb (no. 52) | unit cell = a = 14.26 Å, b = 35.88 Å c = 14.2 Å; Z = 16 | color = | colour = Yellow | habit = Occurs as acicular to elongated bladed crystals, flattened on {010}, also as radiating fibrous clusters and spherulites, pseudotetragonal | twinning = | cleavage = Distinct prismatic | fracture = | tenacity = | mohs = 1–2 | lustre = Waxy to silky | streak = Yellow | diaphaneity = Transparent to translucent | gravity = 4.1 | density = | polish = | opticalprop = Biaxial (−) | refractive = nα = 1.596 nβ = 1.603 nγ = 1.606 | birefringence = δ = 0.010 | pleochroism = X = colorless; Y = pale yellow-green; Z = yellow-green | 2V = Measured: 60° | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = 25px Radioactive greater than 70 Bq/g | references = }} Weeksite is a naturally occurring uranium silicate mineral with the chemical formula: K2(UO2)2Si6O15•4(H2O), potassium uranyl silicate. Weeksite has a Mohs hardness of 1–2. It was named for USGS mineralogist Alice Mary Dowse Weeks (1909–1988).

==Appearance== Weeksite is visually similar to other uranium minerals such as carnotite and zippeite, both being encrustations that form on other rocks (usually sandstones or limestones).