Clinozoisite

(repeating unit)Ca2Al3(Si2O7)(SiO4)O(OH)IMA symbolCzo[1]Strunz classification9.BG.05aDana classification58.2.1a.4Crystal systemMonoclinicCrystal classPrismatic (2/m)
(same H-M symbol)Space groupP21/mUnit cella = 8.879, b = 5.583
c = 10.155 [Å]; β = 115.50°; Z = 2IdentificationColorColorless, green, gray, light green, yellow green, pinkCrystal habitElongated primatic crystals, striated; granular to fibrousTwinningLamellar on {100} uncommonCleavagePerfect on {001}FractureIrregular/unevenTenacityBrittleMohs scale hardness6–7LusterVitreousStreakGrayish whiteDiaphaneityTransparent to translucentSpecific gravity3.3–3.4Optical propertiesBiaxial (+)Refractive indexnα = 1.706 – 1.724 nβ = 1.708 – 1.729 nγ = 1.712 – 1.735Birefringenceδ = 0.006 – 0.0112V angle14 to 90° measuredReferences[2][3][4]

Clinozoisite is a complex calcium aluminium sorosilicate mineral with formula: Ca2Al3(Si2O7)(SiO4)O(OH). It forms a continuous solid solution series with epidote by substitution of iron(III) in the aluminium (m3 site) and is also called aluminium epidote.[2]

Clinothulite is a manganese bearing variety with a pinkish hue due to substitution of Mn(III) in the aluminium site.[5]

It was originally discovered in 1896 in East Tyrol, Austria, and is so-named because of its resemblance to zoisite and its monoclinic crystal structure.[2]

It occurs in rocks which have undergone low to medium grade regional metamorphism and in contact metamorphism of high calcium sedimentary rocks. It also occurs in saussurite alteration of plagioclase.[3]

Jadeite bearing pyroxene minerals have suggested clinozoisite and paragonite are associated and derived from lawsonite releasing quartz and water via the following reaction:[6]

4 CaAl 2 Si 2 O 8 ( H 2 O ) 2 + NaAlSi 2 O 6 ↽ − − ⇀ 2 Ca 2 Al 3 Si 3 O 12 ( OH ) + NaAl 3 Si 3 O 10 ( OH ) 2 + SiO 2 + 6 H 2 O {\displaystyle {\ce {4CaAl2Si2O8(H2O)2 + NaAlSi2O6 <=> 2Ca2Al3Si3O12(OH) + NaAl3Si3O10(OH)2 + SiO2 + 6H2O}}}

References

  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ a b c Clinozoisite on Mindat.org
  3. ^ a b "Clinozoisite in the Handbook of Mineralogy" (PDF). Archived from the original (PDF) on 2015-09-24. Retrieved 2014-03-24.
  4. ^ Clinozoisite data on Webmineral
  5. ^ Clinothulite on Mindat
  6. ^ Deer, William A. (1997). Single-chain Silicates, Volume 2A. Geological Society of London. p. 477.
  • Nesse, William D., "Introduction to Mineralogy," (c)2000 Oxford University Press ISBN 0-19-510691-1


  • v
  • t
  • e