Fundamental Minerals

Sialic Minerals

Feldspars

Feldspathoids

Quartz

Femic Minerals

Spodumene

Accessory Minerals

Rare Accessory

Alteration Products

Microstructures

Rocks

Jacupiranga complex

Clinopyroxene - XYZ₂O₆

Optical properties:

• Colour and Pleochroism: Usually colourless, gray, pale green or pale brown, darker colours associated with Fe-rich varieties titanaugite is more distinctly coloured from brown/pink to violet.
• Form: Form stubby prisms elongate along the c-axis, basal sections are 4 or 8 sided and show two cleavages at 90.°
• Cleavage: Parallel to {110}, which intersect at 90°.
• Twinning: Simple and lamellar twins and composition planes, which in combination may form a herringbone pattern.
• Alteration: Commonly alter to uralite (a light coloured amphibole), or may alter to serpentine, chlorite, biotite, carbonates and /or other silicates.
• Relief: High positive.
• Distinguishing Features: Inclined extinction, higher birefringence, 2nd order interference colours, low 2V, optically positive in comparison with opx.

For structural characteristics and for the classification of the Pyroxene group of minerals see the page structural characteristics and classification

Bibliography

• Cox et al. (1979): The Interpretation of Igneous Rocks, George Allen and Unwin, London.
• Howie, R. A., Zussman, J., & Deer, W. (1992). An introduction to the rock-forming minerals (p. 696). Longman.
• Le Maitre, R. W., Streckeisen, A., Zanettin, B., Le Bas, M. J., Bonin, B., Bateman, P., & Lameyre, J. (2002). Igneous rocks. A classification and glossary of terms, 2. Cambridge University Press.
• Middlemost, E. A. (1986). Magmas and magmatic rocks: an introduction to igneous petrology.
• 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.

Photo
Pyroxene in basal section (with colorless apatite inclusions) in a xenolith from Vulsini volcano, Italy. PPL image, 2x (Field of view = 7mm)	Pyroxene in basal section (with colorless apatite inclusions) in a xenolith from Vulsini volcano, Italy. PPL image, 10x (Field of view = 2mm)	Pyroxene in basal section (with colorless apatite inclusions) in a xenolith from Vulsini volcano, Italy. PPL image, 10x (Field of view = 2mm)
Aegirine (grass-green) crystals in a alkaline syenite from Murun massif, Siberia, Russia. PPL image, 2x (Field of view = 7mm)	Aegirine (green) crystals in a alkaline syenite from Murun massif, Siberia, Russia. XPL image, 2x (Field of view = 7mm)	Aegirine (grass-green) crystals in a alkaline syenite from Murun massif, Siberia, Russia. PPL image, 2x (Field of view = 7mm)
Aegirine (grass-green) crystals in a alkaline syenite from Murun massif, Siberia, Russia. PPL image, 2x (Field of view = 7mm)	Aegirine (grass-green) crystals in a alkaline syenite from Murun massif, Siberia, Russia. PPL image, 2x (Field of view = 7mm)	Aegirine (grass-green) crystals in a alkaline syenite from Mnt. Flora, Lovozero massif, Kola, Russia. PPL image, 10x (Field of view = 2mm)
Aegirine (grass-green) crystals in a alkaline syenite from Mnt. Flora, Lovozero massif, Kola, Russia. XPL image, 10x (Field of view = 2mm)	Aegirine crystal (zoned basal section) in a alkaline syenite from Mnt. Flora, Lovozero massif, Kola, Russia. PPL image, 10x (Field of view = 2mm)	Aegirine crystal (zoned basal section) in a alkaline syenite from Mnt. Flora, Lovozero massif, Kola, Russia. XPL image, 10x (Field of view = 2mm)
Aegirine (grass-green) crystals. Brandberg Complex (Namibia). PPL image, 2x (Field of view = 7mm)	Aegirine (high interference colors) crystals in a fine-grained matrix made of quartz and feldspar (I order gray). Brandberg Complex (Namibia). XPL image, 2x (Field of view = 7mm)	Aegirine (grass-green) crystals. Brandberg Complex (Namibia). PPL image, 2x (Field of view = 7mm)
Aegirine (high interference colors) crystals in a fine-grained matrix made of quartz and feldspar (I order gray). Brandberg Complex (Namibia). XPL image, 2x (Field of view = 7mm)	Aegirine (grass-green) crystals. Brandberg Complex (Namibia). PPL image, 2x (Field of view = 7mm)	Aegirine (high interference colors) crystals in a fine-grained matrix made of quartz and feldspar (I order gray). Brandberg Complex (Namibia). XPL image, 2x (Field of view = 7mm)
Leucite (clorless) and clinopyroxene crystals in a foidolite with leucite. PPL image, 2x (Field of view = 7mm)	Leucite and clinopyroxene crystals in a foidolite with leucite. XPL image. 2x (Field of view = 7mm)	Leucite (clorless) and clinopyroxene crystals in a foidolite with leucite. PPL image, 2x (Field of view = 7mm)
Leucite and clinopyroxene crystals in a foidolite with leucite. XPL image 2x (Field of view = 7mm)	Leucite (clorless) and clinopyroxene crystals. PPL image, 2x (Field of view = 7mm)	Leucite and clinopyroxene crystals in a foidolite with leucite. XPL image. 2x (Field of view = 7mm)
Augite (pink), nepheline (colorless) and Apatite (elongated, colorless crystals). Cape Verde. PPL image, 2x (Field of view = 7mm)	Augite and nepheline (grey). Cape Verde. XPL image, 2x (Field of view = 7mm)	Augite (pink) and nepheline (colorless). Cape Verde. PPL image, 2x (Field of view = 7mm)
Augite and nepheline (grey). Cape Verde. XPL image, 2x (Field of view = 7mm)	Augite and nepheline (grey). Cape Verde. XPL image, 2x (Field of view = 7mm)	Augite and nepheline (grey). Cape Verde. XPL image, 2x (Field of view = 7mm)
Clinopyroxene crystals in a gabbro. PPL image, 2x (Field of view = 7mm)	Clinopyroxene crystals in a gabbro. XPL image, 2x (Field of view = 7mm)	Clinopyroxene crystals in a gabbro. PPL image, 2x (Field of view = 7mm)
Clinopyroxene crystals in a gabbro. XPL image, 2x (Field of view = 7mm)	Clinopyroxene crystals in a gabbro. XPL image, 2x (Field of view = 7mm)	Resorbed olivine crystal in a gabbro, Antarctica. XPL image, 2x (Field of view = 7mm)
Coarse-grained augite crystals and sericitized plagioclase in a augite-bearing gabbro. PPL image, 2x (Field of view = 7mm)/td>	Coarse-grained augite crystals and plagioclase in a augite-bearing gabbro. XPL image, 2x (Field of view = 7mm)/td>	Coarse-grained augite crystals and sericitized plagioclase in a augite-bearing gabbro. PPL image, 2x (Field of view = 7mm)/td>
Coarse-grained augite crystals and sericitized plagioclase in a augite-bearing gabbro. PPL image, 2x (Field of view = 7mm)/td>	Coarse-grained augite crystals and sericitized plagioclase in a augite-bearing gabbro. PPL image, 2x (Field of view = 7mm)/td>	Coarse-grained augite crystals and sericitized plagioclase in a augite-bearing gabbro. PPL image, 2x (Field of view = 7mm)/td>