Metamorphic Minerals

Texture and Microstructure

Metamorphic Rocks

Sapphirine - (Mg,Fe²⁺,Fe³⁺,Al)₈O₂[(Al,Si)₆O₁₈]

Sapphirine, in allusion to its sapphire-like blue color, was first collected by K.L. Giesecke at the old harbour of Fiskenæsset, West Greenland on 5 August 1890. He called it "blauer Diamantspath (saphirin)". Later Stromeyer (1819, 1821) gave the first description of Giesecke’s mineral. He later changed the spelling of the name to the current one with a double p: sapphirine. Sapphirine is a high-temperature minerals of regional metamorphism ore contact metamorphism. It is characteristic of the granulite-amphibolite facies and silica poor, Mg-rich rocks. It appears in schist, gneissen, granulite, amphibolite and hornfels with biotite, corundum, cordierite, sillimanite.

Sapphirine remains stable up to pressures of about 17-25 Kbar and up to temperatures of 1000°C; Beyond that limit, Sapphirine dissociates in pyrope, spinel and corundum:

3Mg₂Al₄SiO₁₀ (sapphirine) = Mg₃Al₂Si₃O₁₂ (pyrope) + 3MgAl₂O₄ (spinel) + 2Al₂O₃ (corundum)

Optical properties:

• Form: Usually occurs as granular aggregate
• Color: Colourless , pale green, or blue
• Relief: High
• Interference colors: Low, sometime indigo-gray color

Bibliography

• Bucher, K., & Grapes, R. (2011). Petrogenesis of metamorphic rocks. Springer Science & Business Media.
• Fossen, H. (2016). Structural geology. Cambridge University Press.
• Howie, R. A., Zussman, J., & Deer, W. (1992). An introduction to the rock-forming minerals (p. 696). Longman.
• Passchier, Cees W., Trouw, Rudolph A. J: Microtectonics (2005).
• Philpotts, A., & Ague, J. (2009). Principles of igneous and metamorphic petrology. Cambridge University Press.
• Shelley, D. (1993). Igneous and metamorphic rocks under the microscope: classification, textures, microstructures and mineral preferred-orientations.
• Vernon, R. H. & Clarke, G. L. (2008): Principles of Metamorphic Petrology. Cambridge University Press.
• Vernon, R. H. (2018). A practical guide to rock microstructure. Cambridge university press.

Orthopyroxene (light brown), sapphirine (gree-blue), biotite (dark brown) and quartz (colorless). Sapphirine granulite from "Valle Codera", Gruf massif. PPL image, 1x (Field of view = 9mm)	Orthopyroxene (light brown), sapphirine (gree-blue), biotite (dark brown), garnet (with opx–cordierite symplectites) and quartz (colorless). Sapphirine granulite from "Valle Codera", Gruf massif. PPL image, 1x (Field of view = 9mm)	Orthopyroxene (light brown), sapphirine (gree-blue), biotite (dark brown), garnet (with opx–cordierite symplectites) and quartz (colorless). Sapphirine granulite from "Valle Codera", Gruf massif. PPL image, 1x (Field of view = 9mm)
Orthopyroxene (light brown), sapphirine (gree-blue), biotite (dark brown) and quartz (colorless). Sapphirine granulite from "Valle Codera", Gruf massif. PPL image, 1x (Field of view = 9mm)	Orthopyroxene, sapphirine biotite and quartz. Sapphirine granulite from "Valle Codera", Gruf massif. XPL image, 1x (Field of view = 9mm)	Orthopyroxene (light brown), sapphirine (gree-blue), biotite (dark brown) and quartz (colorless). Sapphirine granulite from "Valle Codera", Gruf massif. PPL image, 1x (Field of view = 9mm)
Orthopyroxene (light brown), sapphirine (gree-blue), biotite (dark brown) quartz and cordierite (colorless). Sapphirine granulite from "Valle Codera", Gruf massif. PPL image, 2x (Field of view = 7mm)	Orthopyroxene, sapphirine, biotite quartz and cordierite (both I order gray). Sapphirine granulite from "Valle Codera", Gruf massif. PPL image, 2x (Field of view = 7mm)	Orthopyroxene (light brown), sapphirine (gree-blue), biotite (dark brown) quartz and cordierite (colorless). Sapphirine granulite from "Valle Codera", Gruf massif. PPL image, 2x (Field of view = 7mm)
Orthopyroxene (light brown), sapphirine (gree-blue), biotite (dark brown), garnet (with opx–cordierite symplectites) and quartz (colorless). Sapphirine granulite from "Valle Codera", Gruf massif. PPL image, 2x (Field of view = 7mm)	Orthopyroxene, sapphirine biotite garnet (with opx–cordierite symplectites) and quartz. Sapphirine granulite from "Valle Codera", Gruf massif. XPL image, 2x (Field of view = 7mm)	Orthopyroxene (light brown), sapphirine (gree-blue), biotite (dark brown) quartz and cordierite (colorless). Sapphirine granulite from "Valle Codera", Gruf massif. PPL image, 2x (Field of view = 7mm)
Orthopyroxene (light brown), sapphirine (gree-blue), biotite (dark brown) quartz and cordierite (colorless). Sapphirine granulite from "Valle Codera", Gruf massif. PPL image, 2x (Field of view = 7mm)	Orthopyroxene (light brown), sapphirine (gree-blue), biotite (dark brown) quartz and cordierite (colorless). Sapphirine granulite from "Valle Codera", Gruf massif. PPL image, 2x (Field of view = 7mm)	Orthopyroxene, sapphirine, biotite quartz and cordierite (both I order gray). Sapphirine granulite from "Valle Codera", Gruf massif. PPL image, 2x (Field of view = 7mm)
Orthopyroxene (light brown), sapphirine (gree-blue), biotite (dark brown) quartz and cordierite (colorless). Sapphirine granulite from "Valle Codera", Gruf massif. PPL image, 2x (Field of view = 7mm)	Twinned sapphirine (gree-blue) crystal enclosed in orthopyroxene (light brown). Sapphirine granulite from "Valle Codera", Gruf massif. PPL image, 10x (Field of view = 2mm)	Twinned sapphirine crystal enclosed in orthopyroxene. Sapphirine granulite from "Valle Codera", Gruf massif. XPL image, 10x (Field of view = 2mm)
Twinned sapphirine (gree-blue) crystal enclosed in orthopyroxene (light brown). Sapphirine granulite from "Valle Codera", Gruf massif. PPL image, 10x (Field of view = 2mm)	Twinned sapphirine crystal enclosed in orthopyroxene. Sapphirine granulite from "Valle Codera", Gruf massif. XPL image, 10x (Field of view = 2mm)	Sapphirine (gree-blue) crystal enclosed in orthopyroxene (light brown). Sapphirine granulite from "Valle Codera", Gruf massif. PPL image, 10x (Field of view = 2mm)
Sapphirine (gree-blue) crystals, orthopyroxene (light brown), biotite (dark brown) quartz and cordierite (colorless). Sapphirine granulite from "Valle Codera", Gruf massif. PPL image, 10x (Field of view = 2mm)	Sapphirine (gree-blue) crystal, orthopyroxene (light brown), biotite (dark brown) quartz and cordierite (colorless). Sapphirine granulite from "Valle Codera", Gruf massif. PPL image, 10x (Field of view = 2mm)	Sapphirine (gree-blue) crystal, orthopyroxene (light brown), biotite (dark brown) quartz and cordierite (colorless). Sapphirine granulite from "Valle Codera", Gruf massif. PPL image, 10x (Field of view = 2mm)
Sapphirine (green) corona on Sillimanite (beige), the colorless crystals are Cordierite. PPL image, 10x (Field of view = 2mm)	Sapphirine (green) corona on Sillimanite (high interference colors), the gray crystals are Cordierite. PPL image, 10x (Field of view = 2mm)	Sapphirine (green) corona on Sillimanite (beige), the colorless crystals are Cordierite. PPL image, 10x (Field of view = 2mm)
Sapphirine (green) corona on Sillimanite (high interference colors), the gray crystals are Cordierite. XPL image, 10x (Field of view = 2mm)	Sapphirine (green) corona on Sillimanite (beige), the colorless crystals are Cordierite and the high relief colorless crystal is Corundum. PPL image, 10x (Field of view = 2mm)	Sapphirine (green) corona on Sillimanite (high interference colors), the gray crystals are Cordierite and the yellow, anhedral crystal is Corundum. XPL image, 10x (Field of view = 2mm)
Sapphirine (green) corona on Sillimanite (beige), the colorless crystals are Cordierite. PPL image, 10x (Field of view = 2mm)	Sapphirine (green) corona on Sillimanite (high interference colors), the gray crystals are Cordierite. XPL image, 10x (Field of view = 2mm)	Sapphirine (green) corona on Sillimanite (beige), the colorless crystals are Cordierite. PPL image, 10x (Field of view = 2mm)
Sapphirine (green) corona on Sillimanite (high interference colors), the gray crystals are Cordierite. XPL image, 10x (Field of view = 2mm)	Sapphirine (green) corona on Sillimanite (beige), the colorless crystals are Cordierite. PPL image, 10x (Field of view = 2mm)	Sapphirine (green) corona on Sillimanite (high interference colors), the gray crystals are Cordierite. XPL image, 10x (Field of view = 2mm)
Sapphirine (green) corona on Sillimanite (beige), the colorless crystals are Cordierite. PPL image, 10x (Field of view = 2mm)	Sapphirine (green) corona on Sillimanite (beige), the colorless crystals are Cordierite. PPL image, 10x (Field of view = 2mm)	Sapphirine (green) corona on Sillimanite (beige), the colorless crystals are Cordierite. PPL image, 10x (Field of view = 2mm)
Sapphirine (green) corona on Sillimanite (beige), the colorless crystals are Cordierite. PPL image, 2x (Field of view = 7mm)	Sapphirine (green) corona on Sillimanite (high interference colors), the gray crystals are Cordierite. XPL image, 2x (Field of view = 7mm)	Sapphirine (green) corona on Sillimanite (beige), the colorless crystals are Cordierite and the high relief colorless crystal is Corundum. PPL image, 10x (Field of view = 2mm)
Sapphirine (green) corona on Sillimanite (high interference colors), the gray crystals are Cordierite and the yellow, anhedral crystal is Corundum. XPL image, 10x (Field of view = 2mm)	Sapphirine (green) corona on Sillimanite (high interference colors), the gray crystals are Cordierite and the yellow, anhedral crystal is Corundum. XPL image, 10x (Field of view = 2mm)	Sapphirine (green) corona on Sillimanite (beige), the colorless crystals are Cordierite and the high relief colorless crystals are Corundum. PPL image, 10x (Field of view = 2mm)
Sapphirine (green) corona on Sillimanite (high interference colors), the gray crystals are Cordierite and the yellow, anhedral crystals are Corundum. XPL image, 10x (Field of view = 2mm)	Sapphirine (green) corona on Sillimanite (beige), the colorless crystals are Cordierite. PPL image, 2x (Field of view = 7mm)	Sapphirine (green) corona on Sillimanite (high interference colors), the gray crystals are Cordierite. XPL image, 2x (Field of view = 7mm)

Metamorphic Minerals

Texture and Microstructure

Metamorphic Rocks

Sapphirine - (Mg,Fe2+,Fe3+,Al)8O2[(Al,Si)6O18]

Sapphirine - (Mg,Fe²⁺,Fe³⁺,Al)₈O₂[(Al,Si)₆O₁₈]