pentagonite
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Pentagonite is a rare phyllosilicate mineral with formula Ca(VO)Si4O10·4H2O. Its characteristic blue color is due to the presence of the vanadyl () cation in its crystal lattice. The oxidation state of vanadium in the vanadyl cation is +4; therefore, it is a divalent cation. It was named for the unusual twinning called a fiveling with an apparent five-fold symmetry. It is a dimorph of cavansite.
Key facts
- Mineral.name
- Pentagonite
- Mineral.category
- Phyllosilicate minerals
- Mineral.image
- Pentagonite-177796.jpg
- Mineral.formula
- Ca(VO)Si4O10·4H2O
- Mineral.IMAsymbol
- Ptg
- Mineral.strunz
- 9.EA.55
- Mineral.system
- Orthorhombic
- Mineral.class
- Pyramidal (mm2) (same H-M symbol)
- Mineral.symmetry
- Ccm21
- Mineral.unit cell
- a = 10.386(4) Å, b = 14.046(7) Å, c = 8.975(2) Å; Z = 4
- Mineral.color
- Greenish blue
- Mineral.habit
- Prismatic crystals, often as radiating clusters
- Mineral.twinning
- Multiple twins producing a pseudo-pentagonal symmetry
- Mineral.cleavage
- Good on {010}
- Mineral.tenacity
- Brittle
- Mineral.mohs
- 3 - 4
- Mineral.luster
- Vitreous
- Mineral.diaphaneity
- Transparent
via Wikipedia infobox
Wikidata facts
- Image
- Pentagonite-ind36b.jpg
Show 5 more facts
- Nickel-Strunz 9th edition (updated 2009)
- 9.EA.55
- Nickel-Strunz '10th ed', review of (9th ed/ 2009 update)
- 9.EA.55
- Commons category
- Pentagonite
- IMA Mineral Symbol
- Ptg
- chemical formula
- Ca(VO)Si₄O₁₀ * 4H₂O
Sources (1)
via Wikidata · CC0
~2 min read
Article
1 sectionsContents
- References
{{Infobox mineral | name = Pentagonite | category = Phyllosilicate minerals | image = Pentagonite-177796.jpg | alt = | caption = | formula = Ca(VO)Si4O10·4H2O | IMAsymbol = Ptg | strunz = 9.EA.55 | system = Orthorhombic | class = Pyramidal (mm2) (same H-M symbol) | symmetry = Ccm21 | unit cell = a = 10.386(4) Å, b = 14.046(7) Å, c = 8.975(2) Å; Z = 4 | color = Greenish blue | habit = Prismatic crystals, often as radiating clusters | twinning = Multiple twins producing a pseudo-pentagonal symmetry | cleavage = Good on {010} | tenacity = Brittle | mohs = 3 - 4 | luster = Vitreous | streak = | diaphaneity = Transparent | gravity = 2.33 | density = | polish = | opticalprop = Biaxial (-) | refractive = nα = 1.533 nβ = 1.544 nγ = 1.547 | birefringence = δ = 0.014 | 2V = Measured: 50° | pleochroism = Visible: X=Z= colorless Y= blue | references = }}
Pentagonite is a rare phyllosilicate mineral with formula Ca(VO)Si4O10·4H2O. Its characteristic blue color is due to the presence of the vanadyl () cation in its crystal lattice. The oxidation state of vanadium in the vanadyl cation is +4; therefore, it is a divalent cation. It was named for the unusual twinning called a fiveling with an apparent five-fold symmetry. It is a dimorph of cavansite.