norbergite

{{Infobox mineral

| name = Norbergite

| category = Nesosilicates

| image = Norbergite-Calcite-290476.jpg

| caption = Norbergite crystals on calcite from Oakssaung Hill, Mogok, Mandalay, Burma (size: 4.2 x 3.3 x 2.3 cm)

| formula = Mg₃(SiO₄)(F,OH)₂

| IMAsymbol = Nrb{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols|journal=Mineralogical Magazine|volume=85|issue=3 |pages=291–320|doi=10.1180/mgm.2021.43 |bibcode=2021MinM...85..291W |s2cid=235729616 |doi-access=free}}

| molweight = 202.00 g/mol

| strunz = 9.AF.40

| dana =

| system = Orthorhombic

| class = Dipyramidal (mmm)
H-M symbol: (2/m 2/m 2/m)

| symmetry = Pnma

| unit cell = a = 8.747(6), b = 4.710(4)
c = 10.271(8) [Å]; Z = 4

| color = Tan, yellow, yellow-orange, orange-brown, pink with purplish tint, white

| habit = Granular, tabular crystals rare

| twinning =

| cleavage =

| fracture = Uneven to subconchoidal

| tenacity = Brittle

| mohs = 6–6.5

| luster = Vitreous to resinous

| refractive = n_α = 1.563 n_β = 1.567 n_γ = 1.590

| opticalprop = Biaxial (+)

| birefringence = δ = 0.027

| pleochroism = Pleochroism: X = pale yellow; Y = very pale yellow; Z = colorless

| 2V = 44 – 50°

| streak = White

| gravity = 3.177

| density =

| melt =

| fusibility =

| diagnostic =

| solubility =

| diaphaneity = Transparent to translucent

| other = May fluoresce canary-yellow under SW UV

| references =[http://webmineral.com/data/Norbergite.shtml#.UjWB0n907zM Norbergite data on Webmineral][http://www.mindat.org/min-2925.html Norbergite on Mindat.org][http://www.handbookofmineralogy.com/pdfs/norbergite.pdf Norbergite in the Handbook of Mineralogy]

}}

Norbergite is a nesosilicate mineral with formula Mg₃(SiO₄)(F,OH)₂. It is a member of the humite group.

It was first described in 1926 for an occurrence in the Östanmoss iron mine in Norberg, Västmanland, Sweden, for which it is named.{{cite web|url=http://www.merriam-webster.com/dictionary/norbergite|title=Norbergite|work=merriam-webster.com|publisher=Merriam-Webster|accessdate=15 September 2013}}

It occurs in contact metamorphic zones in carbonate rocks intruded by plutonic rocks or pegmatites supplying the fluorine. Associated minerals include dolomite, calcite, tremolite, grossular, wollastonite, forsterite, monticellite, cuspidine, fluoborite, ludwigite, fluorite and phlogopite.