Stellerite

{{Short description|Zeolite mineral}}

{{Infobox mineral

| name = Stellerite

| category = Tectosilicate minerals, zeolite group, stilbite subgroup

| boxwidth =

| boxbgcolor =

| image = Stellerite - Takat, Imilchil, Midelt Province, Drâa-Tafilalet Region, Morocco.jpg

| imagesize = 270px

| caption =

| formula = Ca(Al₂Si₇O₁₈)·7H₂O

| IMAsymbol = Ste{{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 =

| strunz = 9.GE.15

| system = Orthorhombic

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

| symmetry = Fmmm

| unit cell =

| color = Colorless to white, pink, orange

| habit = Spherical, Stellate, Tabular

| twinning =

| cleavage = Perfect on {010}

| fracture = Uneven

| tenacity =

| mohs = 4.5

| luster = Pearly

| refractive =

| opticalprop = Biaxial (-), a=1.4848, b=1.4864-1.4964, g=1.4979

| birefringence = δ = 0.013

| pleochroism =

| streak = white

| gravity = approximately 2.2

| density = 2.13 g/cm3

| melt =

| fusibility =

| diagnostic =

| solubility =

| diaphaneity = Transparent to translucent

| other =

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}}

Stellerite is a rare mineral discovered by and named after Georg Wilhelm Steller, a German explorer and zoologist.{{cite journal |last1=Pabst |first1=Adolf |title=The relation of stellerite and epidesmine to stilbite |journal=Mineralogical Magazine and Journal of the Mineralogical Society |date=March 1939 |volume=25 |issue=164 |pages=271–276 |doi=10.1180/minmag.1939.025.164.06|bibcode=1939MinM...25..271P }} The mineral has a general formula of Ca[Al₂Si₇O₁₈]·7H₂O.{{Cite web |title=Stellerite |work=PubChem |publisher=National Library of Medicine |date= |access-date=19 October 2023 |url= https://pubchem.ncbi.nlm.nih.gov/compound/Stellerite#section=Synonyms}} Like most rare minerals, there are few commercial uses for stellerite. Mineral collectors are lucky to find it in good enough crystal form. Zeolites, including stellerite, have been studied using a dehydration process to gauge the potential use of their phases as molecular sieves, sorbents, and catalysts.{{cite journal |last1=Arletti |first1=R. |last2=Mazzucato |first2=E. |last3=Vezzalini |first3=G. |title=Influence of dehydration kinetics on T-O-T bridge breaking in zeolites with framework type STI: The case of stellerite |journal=American Mineralogist |date=1 April 2006 |volume=91 |issue=4 |pages=628–634 |doi=10.2138/am.2006.1966|bibcode=2006AmMin..91..628A |hdl=2318/80204 |s2cid=36048763 |hdl-access=free }} Its occurrences are in cavities of andesite as sheaf-like clusters of small crystals.