| 词条 | Aphthitalite |
| 释义 |
| name = Aphthitalite | image = Aphthitalite-180031.jpg | alt = | caption = Aphthitalite, collected from Ghom Salt Dome, Qom Province, Iran | category = Sulfate mineral | formula = (K,Na)3Na(SO4)2 | molweight = | strunz = 7.AC.35 | dana = | system = Trigonal | class = Hexagonal scalenohedral ({{overline|3}}m) H-M symbol: ({{overline|3}} 2/m) | symmetry = P{{overline|3}}m | unit cell = a = 5.67, c = 7.33 [Å]; Z = 1 | color = White, colorless; gray, blue, green due to inclusions and impurities | habit = Tabular crystals (with distorted pseudo-orthorhombic habit); as bladed aggregates and in crusts | twinning = On {0001} or repeated on {11{{overline|2}}0} | cleavage = Fair on {10{{overline|1}}0}, poor on {0001} | fracture = Conchoidal to uneven | tenacity = Brittle | mohs = 3 | luster = Vitreous to resinous | streak = | diaphaneity = Transparent to opaque | gravity = 2.66–2.71 | density = | polish = | opticalprop = Uniaxial (+) (anomalously biaxial) | refractive = nω = 1.487 - 1.491 nε = 1.492 - 1.499 | birefringence = δ = 0.005 | pleochroism = | 2V = | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = In water | impurities = | alteration = | other = | references = [1][2][3] }} Aphthitalite is a potassium sulfate mineral with the chemical formula: (K,Na)3Na(SO4)2. It was first described in 1835 for an occurrence on Mt. Vesuvius, Italy. The name is from the Greek άφθητος, "unalterable", and άλας, "salt", for its stability in air.[1] It occurs as fumarolic incrustations in volcanic environments, as small crystals and masses in evaporite deposits and in guano deposits.[2][3] It occurs associated with thenardite, jarosite, sylvite and hematite in fumaroles; with blodite, syngenite, mirabilite, picromerite, borax and halite in evaporites; and with syngenite, whitlockite, monetite, niter and gypsum in guano deposits.[3] References{{commons category|Aphthitalite}}1. ^1 Mindat.org {{sulfate-mineral-stub}}2. ^1 Webmineral data 3. ^1 2 Handbook of Mineralogy 4 : Sulfate minerals|Potassium minerals|Sodium minerals|Trigonal minerals |
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