Kyanite

kyanite

staurolite

andalusite

sillimanite

Images

Formula: Al₂OSiO₄
Nesosilicate (insular SiO₄ groups), paramorph of andalusite and sillimanite.
Specific gravity: 3.53 to 3.65
Hardness: 5½ to 7
Streak: White
Colour: Blue, green, orange, black
Luminescence: Not usually fluorescent
Solubility: Insoluble in hydrochloric, sulphuric and nitric acid
Environments:

Placer deposits
Metamorphic environments (typical)

Kyanite is a common mineral of high to very high pressure regionally metamorphosed rocks and typically it is found in gneiss and schist. Associated minerals include andalusite and/or sillimanite, garnet, staurolite, talc, mullite, corundum and hornblende (Lauf p180).
It is a common constituent of eclogite, and it also may be found in hornfels and in garnet- omphacite-kyanite occurrences in kimberlite pipes.
Kyanite develops after staurolite and before sillimanite with increasing grade of metamorphism. It is a characteristic mineral of the amphibolite and granulite facies and it is also a mineral of the greenschist, blueschist and eclogite facies.

Localities

At Casey Bay, Napier Complex, Enderby Land, Eastern Antarctica, Antarctica, retrogression of the country rock by the pegmatites occurred under amphibolite facies conditions in aureoles generally no more than a few meters thick. Accessory minerals include biotite, muscovite, hornblende, titanite, magnetite, allanite, beryl, kyanite, sillimanite, garnet, staurolite, tourmaline, dumortierite, and, locally, sodium-bearing cordierite (AM 66.1022_1033).

Alteration

andalusite, sillimanite and kyanite are paramorphs; they are in equilibrium at a pressure of 3.75 kbar and temperature 504^oC (amphibolite facies) (AM78.298-315).
Kyanite is unstable at low pressure.

























anorthite to grossular, kyanite and quartz
3CaAl₂ Si₂O₈ → Ca₃Al₂(SiO₄)₃ + 2Al₂OSiO₄ + SiO₂
At 20 kbar pressure the equilibrium temperature is about 1,000^oC and at 30 kbar it is about 1,400^oC

diaspore and quartz to kyanite and H₂O
2AlO(OH) + SiO₂ ⇌ Al₂OSiO₄ + H₂O
The equilibrium temperature for this reaction at 10 kbar pressure is about 420^oC (greenschist facies), with the equilibrium to the right at higher temperatures, and to the left at lower temperatures (SERC).

enstatite and kyanite to spinel and cordierite
5Mg₂Si₂O₆ + 10Al₂OSiO₄ ⇌ 2MgAl₂O₄ + 4Mg₂Al₄Si₅O₁₈
Increasing temperature favours the forward reaction (SERC).

enstatite, kyanite and quartz to cordierite
Mg₂Si₂O₆ + 2Al₂OSiO₄ + SiO₂ ⇌ Mg₂Al₄Si₅O₁₈
At 6 kbar pressure the equilibrium temperature is about 475^oC (greenschist facies). The equilibrium moves to the right at higher temperatures and to the left at lower temperatures (SERC).

forsterite and kyanite to cordierite and spinel
5Mg₂SiO₄ + 10Al₂OSO₄ ⇌ 3Mg₂Al₄Si₅O₁₈ + 4MgAl₂O₄
At 400^oC the equilibrium pressure for this reaction is about 4 kBars; increasing temperature favours the forward reaction (SERC).

forsterite and kyanite to spinel and pyrope
5Mg₂SiO₄ + 4Al₂OSiO₄ ⇌ MgAl₂O₄ + 3Mg₃Al₂ (SiO₄)₃
Increasing temperature favours the forward reaction (SERC).

forsterite, kyanite and quartz to cordierite
Mg₂SiO₄ + 2Al₂OSiO₄ + 2SiO₂ ⇌ Mg₂Al₄Si₅O₁₈
At 6 kbar pressure the equilibrium temperature is about 400^oC (greenschist facies) (SERC).

grossular and kyanite to anorthite and corundum
Ca₃Al₂(SiO₄)₃ + 3Al₂OSiO₄ ⇌ 3CaAl₂Si₂O₈ + Al₂O₃
The equilibrium temperature for this reaction at 10 kbar pressure is about 540^oC (amphibolite facies), with the equilibrium to the right at higher temperatures, and to the left at lower temperatures (SERC).

grossular, kyanite and quartz to anorthite
Ca₃Al₂(SiO₄)₃ + 2Al₂OSiO₄ + SiO₂ ⇌ 3CaAl₂Si₂O₈
The equilibrium temperature for this reaction at 10 kbar pressure is about 510^o (amphibolite facies), with the equilibrium to the right at higher temperatures, and to the left at lower temperatures (SERC).

kaolinite to kyanite, pyrophyllite and H₂O
3Al₂Si₂O₅(OH)₄ ⇌ 2Al₂OSiO₄ + Al₂Si₄O₁₀(OH)₂ + 5H₂O
At 5 kbar pressure the equilibrium temperature for the reaction is about 375^oC (greenschist facies), with the equilibrium to the right at higher temperatures and to the left at lower temperatures (SERC, AM61.699-709).

kaolinite and diaspore to kyanite and H₂O
Al₂Si₂O₅(OH)₄ + 2AlO(OH) ⇌ 2Al₂OSiO₄ + 3H₂O
At 5 kbar pressure the equilibrium temperature for the reaction is about 370^oC (greenschist facies), with the equilibrium to the right at higher temperatures and to the left at lower temperatures (SERC, AM61.699-709).

kyanite and enstatite to cordierite and pyrope
6Al₂OSiO₄ + 5Mg₂Si₂O₆ ⇌ 2Mg₂Al₄Si₅O₁₈ + 2Mg₃Al₂(SiO₄)₃
Increasing temperature favours the forward reaction (SERC).

kyanite and enstatite to cordierite and corundum
3Al₂O(SiO₄) + Mg₂Si₂O₆ ⇌ Mg₂Al₄Si₅O₁₈ + Al₂O₃
The equilibrium temperature for this reaction at 6 kbar pressure is about 520^oC (amphibolite facies), with equilibrium to the right at higher temperatures, and to the left at lower temperatures (SERC).

kyanite and enstatite to quartz and pyrope
2Al₂O(SiO₄) + 3Mg₂Si₂O₆ ⇌ 2SiO₂ + 2Mg₃Al₂(SiO₄)₃
The equilibrium temperature for this reaction at 14 kbar pressure is about 950^oC (granulite facies), with equilibrium to the right at higher temperatures, and to the left at lower temperatures (SERC).

kyanite and forsterite to enstatite and spinel
2Al₂OSiO₄ + 4Mg₂SiO₄ ⇌ 3Mg₂Si₂O₆ + 2MgAl₂O₄
Increasing temperature favours the forward reaction (SERC).

kyanite, forsterite and cordierite to pyrope
2Al₂OSiO₄ + 5Mg₂SiO₄ + Mg₂Al₄Si₅O₁₈ ⇌ 4Mg₃Al₂(SiO₄)₃
Increasing pressure favours the forward reaction (SERC).

kyanite and pyrope to cordierite and spinel
2Al₂OSiO₄ + Mg₃Al₂(SiO₄)₃ ⇌ Mg₂Al₄Si₅O₁₈ + MgAl₂O₄
Increasing temperature favours the forward reaction (SERC).

kyanite and zoisite to anorthite, corundum and H₂O
2Al₂O(SiO₄) + 2Ca₂Al₃[Si₂O₇][SiO₄]O(OH) ⇌ 4CaAl₂Si₂O₈ + Al₂O₃ + H₂O
The equilibrium temperature for this reaction at 5 kbar pressure is 480^oC (greenschist facies), and at 10 kbar it is about 720^oC (amphibolite facies). The equilibrium is to the right at higher temperatures, and to the left at lower temperatures (SERC, AM61.699-709).

kyanite and zoisite to margarite and anorthite
2Al₂O(SiO₄) + 2Ca₂Al₃[Si₂O₇][SiO₄]O(OH) ⇌ CaAl₂(Al₂Si₂O₁₀)(OH)₂ + Ca(Al₂Si₂O₈)
The equilibrium temperature for this reaction at 6 kbar pressure is about 520^oC (amphibolite facies), and at 9 kbar it is about 675^oC (amphibolite facies). At any pressure the equilibrium is displaced to the right at higher temperatures, and to the left at lower temperatures (SERC, AM61.699-709).

kyanite, zoisite and diaspore to margarite
Al₂OSiO₄ + Ca₂Al₃[Si₂O₇][SiO₄]O(OH) + 3AlO(OH) ⇌ 2CaAl₂(Al₂Si₂O₁₀)(OH)₂
Increasing temperature favours the forward reaction (SERC)

kyanite, zoisite and quartz to anorthite and H₂O
Al₂OSiO₄ + 2Ca₂Al₃[Si₂O₇][SiO₄]O(OH) + SiO₂ ⇌ 4Al₂OSiO₄ + H₂O
Increasing temperature favours the forward reaction (SERC)

lawsonite to zoisite, kyanite, quartz and H₂O
4CaAl₂(Si₂O₇)(OH)₂.H₂ ⇌ 2Ca₂Al₃[Si₂O₇][SiO₄]O(OH) + Al₂OSiO₄ + SiO₂ + 7H₂O
The equilibrium temperature for this reaction at 10 kbar pressure is about 500^oC (greenschist facies), with the equilibrium to the right at higher temperatures, and to the left at lower temperatures (AM61.699-709).

lawsonite and corundum to zoisite, kyanite and H₂O
4CaAl₂(Si₂O₇)(OH)₂.H₂ + Al₂O₃ ⇌ 2Ca₂Al₃[Si₂O₇][SiO₄}O(OH) + 2Al₂OSiO₄ + 7H₂O
The equilibrium temperature for this reaction at 15 kbar pressure is about 570^oC (eclogite facies), with the equilibrium to the right at higher temperatures, and to the left at lower temperatures (AM61.699-709).

lawsonite and kyanite to margarite, pyrophyllite and H₂O
3CaAl₂(Si₂O₇)(OH)₂.H₂ + 4Al₂OSiO₄ ⇌ 3CaAl₂(Al₂Si₂O₁₀)(OH)₂ + Al₂Si₄O₁₀(OH)₂ + 2H₂O
The equilibrium temperature for this reaction at 6.5 kbar pressure is about 390^oC (greenschist facies), with the equilibrium to the right at higher temperatures, and to the left at lower temperatures (AM61.699-709).

lawsonite and kyanite to margarite, quartz and H₂O
CaAl₂(Si₂O₇)(OH)₂.H₂ + Al₂OSiO₄ ⇌ CaAl₂(Al₂Si₂O₁₀)(OH)₂ + SiO₂ + H₂O
The equilibrium temperature for this reaction at 8 kbar pressure is about 450^oC (greenschist facies), with the equilibrium to the right at higher temperatures, and to the left at lower temperatures (AM61.699-709).

lawsonite and margarite to zoisite, kyanite and H₂O
3CaAl₂(Si₂O₇)(OH)₂.H₂ + CaAl₂(Al₂Si₂O₁₀)(OH)₂ ⇌ 2Ca₂Al₃[Si₂O₇][SiO₄]O(OH) + 2Al₂OSiO₄ + 6H₂O
The equilibrium temperature for this reaction at 10 kbar pressure is about 500^oC (greenschist facies), with the equilibrium to the right at higher temperatures, and to the left at lower temperatures (AM61.699-709).

margarite to corundum, zoisite, kyanite and H₂O
4CaAl₂(Al₂Si₂O₁₀)(OH)₂ ⇌ 3Al₂O₃ + 2Ca₂Al₃[Si₂O₇][SiO₄]O(OH) + 2Al₂OSiO₄ + 3H₂O
The equilibrium temperature for this reaction at 10 kbar pressure is about 650^oC (amphibolite facies), with the equilibrium to the right at higher temperatures, and to the left at lower temperatures (SERC, AM61.699-709).

margarite and quartz to anorthite, kyanite and H₂O
CaAl₂(Al₂Si₂O₁₀)(OH)₂ + SiO₂ ⇌ Ca(Al₂Si₂O₈) + Al₂OSiO₄ + H₂O
The equilibrium temperature for this reaction at 5 kbar pressure is about 520^oC (amphibolite facies), with the equilibrium to the right at higher temperatures, and to the left at lower temperatures (SERC, AM61.699-709).

margarite and quartz to zoisite, kyanite and H₂O
4CaAl₂(Al₂Si₂O₁₀)(OH)₂ + 3SiO₂ ⇌ 2Ca₂Al₃[Si₂O₇][SiO₄]O(OH) + 5Al₂OSiO₄ + 3H₂O
The equilibrium temperature for this reaction at 8 kbar pressure is about 510^oC (amphibolite facies), with the equilibrium to the right at higher temperatures, and to the left at lower temperatures (AM61.699-709).

paragonite and quartz to albite, kyanite and H₂O
NaAl₂(Si₃Al)O₁₀(OH)₂ + SiO₂ ⇌ Na(AlSi₃O₈) + Al₂OSiO₄ + H₂O
Increasing temperature favours the forward reaction (AM61.699-709).

pyrophyllite to kyanite, quartz and H₂O
Al₂Si₂O₁₀(OH)₂ ⇌ Al₂OSiO₄ + 3SiO₂ + H₂O
At 9 kbar pressure the equilibrium temperature is about 425^oC (greenschist facies) (AM61.699-709).

pyrophyllite and diaspore to kyanite and H₂O
Al₂Si₄O₁₀(OH)₂ + 6AlO(OH) ⇌ 4Al₂OSiO₄ + 4H₂O
(JVW p 553
This reacton is a higher pressure reaction, occurring above about 1.9 kbar. Increasing temperature favours the forward reaction. At 9 kbar pressure the equilibrium temperature is about 380^oC (greenschist facies) (SERC, AM61.699-709).

quartz, kyanite and forsterite to pyrope
SiO₂ + 2Al₂OSiO₄ + 3Mg₂SiO₄ ⇌ 2Mg₃Al₂(SiO₄)₃
Increasing temperature favours the forward reaction (SERC).

quartz, pyrope and kyanite to cordierite
5SiO₂ + 2Mg₃Al₂(SiO₄)₃ + 4Al₂OSiO₄ ⇌ 3Mg₂Al₄Si₅O₁₈
Increasing temperature favours the forward reaction (SERC).

spinel, kyanite and enstatite to pyrope
2MgAl₂O₄ + 2Al₂OSiO₄ + 5Mg₂Si₂O₆ ⇌ 4Mg₃Al₂(SiO₄)₃
Increasing temperature favours the forward reaction (SERC).

talc and kyanite to cordierite, corundum and H₂O
2Mg3Si₄O₁₀(OH)₂ + 7Al₂OSiO₄ ⇌ 3Mg₂Al₄Si₅O₁₈ + Al₂O₃ + 2H₂O
(DHZ 2A p635)

zoisite and kyanite to margarite and anorthite
2Ca₂Al₃[Si₂O₇][SiO₄]O(OH) + 2Al₂OSiO₄ ⇌ CaAl₂(Al₂Si₂O₁₀)(OH)₂ + 3Al₂OSiO₄
Increasing temperature favours the forward reaction (SERC)

zoisite, kyanite and diaspore to margarite
Ca₂Al₃[Si₂O₇][SiO₄]O(OH) + Al₂OSiO₄ + 3AlO(OH) ⇌ 2CaAl₂(Al₂Si₂O₁₀)(OH)₂
The equilibrium temperature for this reaction at 12 kbar pressure is about 480^oC (blueschist facies), with the equilibrium to the right at higher temperatures, and to the left at lower temperatures (SERC).

zoisite, kyanite and quartz to anorthite and H₂O
2Ca₂Al₃[Si₂O₇][SiO₄]O(OH) + Al₂OSiO₄ + SiO₂ ⇌ 4Ca(Al₂Si₂O₈) + H₂O
The equilibrium temperature for this reaction at 10 kbar pressure is about 690^oC (amphibolite facies), with the equilibrium to the right at higher temperatures, and to the left at lower temperatures (SERC, AM61.699-709).

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