Clinozoisite
From Wikipedia, the free encyclopedia
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]
| Clinozoisite | |
|---|---|
Clinozoisite | |
| General | |
| Category | Sorosilicates Epidote group |
| Formula | Ca2Al3(Si2O7)(SiO4)O(OH) |
| IMA symbol | Czo[1] |
| Strunz classification | 9.BG.05a |
| Dana classification | 58.2.1a.4 |
| Crystal system | Monoclinic |
| Crystal class | Prismatic (2/m) (same H-M symbol) |
| Space group | P21/m |
| Unit cell | a = 8.879, b = 5.583 c = 10.155 [Å]; β = 115.50°; Z = 2 |
| Identification | |
| Color | Colorless, green, gray, light green, yellow green, pink |
| Crystal habit | Elongated primatic crystals, striated; granular to fibrous |
| Twinning | Lamellar on {100} uncommon |
| Cleavage | Perfect on {001} |
| Fracture | Irregular/uneven |
| Tenacity | Brittle |
| Mohs scale hardness | 6–7 |
| Luster | Vitreous |
| Streak | Grayish white |
| Diaphaneity | Transparent to translucent |
| Specific gravity | 3.3–3.4 |
| Optical properties | Biaxial (+) |
| Refractive index | nα = 1.706 – 1.724 nβ = 1.708 – 1.729 nγ = 1.712 – 1.735 |
| Birefringence | δ = 0.006 – 0.011 |
| 2V angle | 14 to 90° measured |
| References | [2][3][4] |
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]
![{\displaystyle {4\,\mathrm {CaAl} {\vphantom {A}}_{\smash[{t}]{2}}\mathrm {Si} {\vphantom {A}}_{\smash[{t}]{2}}\mathrm {O} {\vphantom {A}}_{\smash[{t}]{8}}(\mathrm {H} {\vphantom {A}}_{\smash[{t}]{2}}\mathrm {O} ){\vphantom {A}}_{\smash[{t}]{2}}{}+{}\mathrm {NaAlSi} {\vphantom {A}}_{\smash[{t}]{2}}\mathrm {O} {\vphantom {A}}_{\smash[{t}]{6}}{}\mathrel {\longrightleftharpoons } {}2\,\mathrm {Ca} {\vphantom {A}}_{\smash[{t}]{2}}\mathrm {Al} {\vphantom {A}}_{\smash[{t}]{3}}\mathrm {Si} {\vphantom {A}}_{\smash[{t}]{3}}\mathrm {O} {\vphantom {A}}_{\smash[{t}]{12}}(\mathrm {OH} ){}+{}\mathrm {NaAl} {\vphantom {A}}_{\smash[{t}]{3}}\mathrm {Si} {\vphantom {A}}_{\smash[{t}]{3}}\mathrm {O} {\vphantom {A}}_{\smash[{t}]{10}}(\mathrm {OH} ){\vphantom {A}}_{\smash[{t}]{2}}{}+{}\mathrm {SiO} {\vphantom {A}}_{\smash[{t}]{2}}{}+{}6\,\mathrm {H} {\vphantom {A}}_{\smash[{t}]{2}}\mathrm {O} }}](http://wikimedia.org/api/rest_v1/media/math/render/svg/f171dcd4948f9f96867f1c867f252bc3174101ab)
