Pumpellyite

{{short description|Pumpellyite series}}

{{Infobox mineral

| name = Pumpellyite

| image = Mineraly.sk - pumpellyit.jpg

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| category = Sorosilicate

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| IMAsymbol = Pmp{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols|url=https://www.cambridge.org/core/journals/mineralogical-magazine/article/imacnmnc-approved-mineral-symbols/62311F45ED37831D78603C6E6B25EE0A|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 =

| strunz = 9.BG.20

| dana =

| system = Monoclinic

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

| symmetry = A2/m

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| color = Olive green to bluish green

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| cleavage = Good in two directions

| fracture = Uneven

| tenacity = Brittle

| mohs = 5.5-6

| luster = Vitreous, dull

| streak = White

| diaphaneity = Translucent

| gravity = 3.2

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| references = [https://www.mineralienatlas.de/lexikon/index.php/MineralData?mineral=Pumpellyite Mineralienatlas]

{{cite book |last1=Chesterman |first1=Charles W. |title=The Audubon Society field guide to North American rocks and minerals |date=1978 |publisher=Alfred A. Knopf |location=New York |isbn=0394502698 |page=567}}}}

Pumpellyite is a group of closely related sorosilicate minerals:

• pumpellyite-(Mg): {{chem2|Ca2MgAl2[Si2O6OH][SiO4](OH)2(OH)}}[http://www.mindat.org/min-3309.html Mindat - Pumpellyite-(Mg)]
• pumpellyite-(Fe2+): {{chem2|Ca2Fe(2+)Al2[Si2O6OH][SiO4](OH)2(OH)}}[http://www.mindat.org/min-3307.html Mindat - Pumpellyite-(Fe2+)]
• pumpellyite-(Fe3+): {{chem2|Ca2Fe(3+)Al2[Si2O6OH][SiO4](OH)2O}}[http://www.mindat.org/min-3308.html Mindat - Pumpellyite-(Fe3+)]
• pumpellyite-(Mn2+): {{chem2|Ca2Mn(2+)Al2[Si2O6OH][SiO4](OH)2(OH)}}[http://www.mindat.org/min-3310.html Mindat - Pumpellyite-(Mn2+)]
• pumpellyite-(Al): {{chem2|Ca2AlAl2[Si2O6OH][SiO4](OH)2O}}[http://www.mindat.org/min-27439.html Mindat - Pumpellyite (Al)]

Pumpellyite crystallizes in the monoclinic-prismatic crystal system. It typically occurs as blue-green to olive green fibrous to lamellar masses. It is translucent and glassy with a Mohs hardness of 5.5 and a specific gravity of 3.2. It has refractive indices of n_α=1.674–1.748, n_β=1.675–1.754 and n_γ=1.688–1.764.

Pumpellyite occurs as amygdaloidal and fracture fillings in basaltic and gabbroic rocks in metamorphic terranes. It is an indicator mineral of the prehnite-pumpellyite metamorphic facies. It is associated with chlorite, epidote, quartz, calcite and prehnite.

It was first described in 1925 for occurrences in the Calumet mine, Houghton Co., Keweenaw Peninisula, Michigan, and named for United States geologist Raphael Pumpelly (1837–1923).{{cite book|last1=Huber|first1=N. King|title=The Geologic Story of Isle Royale National Park, USGS Bulletin 1309|date=1975|publisher=U.S. Government Printing Office|location=Washington|page=58}}