Xanthiosite

{{Infobox mineral

| name = Xanthiosite

| category = Arsenate mineral

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| image = Aerugite-154934 cropped.jpg

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| caption = Xanthiosite and aerugite

| formula = Ni₃(AsO₄)₂

| IMAsymbol = Xth{{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 = 453.91 g/mol

| strunz = 8.AB.25

| system = Monoclinic

| class = Prismatic (2/m)
(same H-M symbol)

| symmetry = P2₁/a

| color = Golden yellow

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| mohs = 4

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| gravity = 5.37–5.47

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| diaphaneity = Translucent

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| references =[http://webmineral.com/data/Xanthiosite.shtml Xanthiosite mineral data from Webmineral][http://www.mindat.org/min-4327.html Mindat.org]

}}

Xanthiosite is a nickel arsenate mineral. It was first discovered in Germany in 1858{{cn|date=October 2024}} and named by Gilbert Joseph Adam in 1869.