{{Short description|Arsenate mineral}} {{infobox mineral | name = Adelite | category = Adelite-descloizite group | boxbgcolor = | image = Adelite.jpg | imagesize = | caption = Pinkish crystal aggregates of adelite from the Franklin deposit in Ogdensburg, New Jersey | formula = CaMg(AsO<sub>4</sub>)(OH) |IMAsymbol=Ade<ref>{{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}}</ref> | strunz = 8.BH.35 | dana = 41.5.1.1 | system = Orthorhombic | class = 2 2 2 – Disphenoidal | symmetry = P2<sub>1</sub>2<sub>1</sub>2<sub>1</sub> | unit cell = | color = Colourless, white, grey, bluish grey, yellowish grey, yellow, pale green, pinkish brown, brown | habit = Elongate crystals, massive | twinning = | cleavage = None observed | luster = Vitreous, greasy | diaphaneity =Transparent, translucent | mohs = 5 | gravity = 3.73 to 3.79 | opticalprop = Biaxial (+), colorless (transmitted light) | refractive = | references = <ref name=Mindat>[http://www.mindat.org/min-23.html Mindat.org]</ref>}}
The rare mineral '''adelite,''' is a calcium, magnesium, arsenate with chemical formula CaMgAsO<sub>4</sub>OH. It forms a solid solution series with the vanadium-bearing mineral gottlobite. Various transition metals substitute for magnesium and lead replaces calcium leading to a variety of similar minerals in the ''adelite–duftite group''.
Adelite forms variably colored (blue, green, yellow and grey) crystals in the orthorhombic crystal system. The form is typically massive. It has a Mohs hardness rating of 5 and a specific gravity of 3.73 to 3.79.
It was first described in 1891 from Värmland, Sweden. Its name comes from the Greek word for ''indistinct''.
==Geologic occurrence== Adelite has been found in ore deposits in Algeria, Germany, Italy, Sweden and the US.<ref name=Mindat />
==See also== *Descloizite *List of minerals
==References== {{Wiktionary}} {{Reflist}} *[http://www.mindat.org/min-23.html Mindat.org] *[http://www.webmineral.com/data/Adelite.shtml Webmineral data]
==Bibliography== *<small>Palache, P.; Berman H.; Frondel, C. (1960). "''Dana's System of Mineralogy, Volume II: Halides, Nitrates, Borates, Carbonates, Sulfates, Phosphates, Arsenates, Tungstates, Molybdates, Etc. (Seventh Edition)"'' John Wiley and Sons, Inc., New York, pp. 804–806.</small>
Category:Calcium minerals Category:Magnesium minerals Category:Arsenate minerals Category:Hydroxide minerals Category:Orthorhombic minerals Category:Minerals in space group 19
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