Clinopyroxene Thin Section

Clinopyroxenes and orthopyroxenes are easily distinguished in thin section by their extinction angles.

Clinopyroxene thin section. The keys to identifying calcic clinopyroxene are normally its high relief pale green sometimes clear or light brown color middle second order interference colors and near 90 o cleavage seen in some views. Shape isotropy and relief distinctive. Simple twin in basal section of clinopyroxene.

Low birefringence first order colors. 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. The rock illustrated in these images contains both clinopyroxene and orthopyroxene and the significantly higher cr 2 o 3 content of the clinopyroxene in this sample gives it a pale green colour in plane polarized light whereas the cr poor orthopyroxene is colourless a.

Distinguishing the different pyroxenes and olivine can sometimes be difficult. A thin section of green pyroxene mantle peridotite xenolith from san carlos indian reservation gila co arizona usa. Parallel extinction in longitudinal sections pale pink to green pleochroism.

Crystals form stubby prisms elongate along the c axis basal sections are 4 or 8 sided and show two cleavages at 90. A diagnostic feature of members of the pyroxene group is the 110 cleavage that. Feldspars clinopyroxene garnet biotite and hornblende.

Xpl image 10x field of view 2mm orthopyroxene crystal with clinopyroxene rim in a dacite. Acicular crystals of cr diopside. Ca mg fe na mg fe al si al 2 o 6.

Loch borrolan carbonatite. The xenolith is dominated by green peridot olivine together with black orthopyroxene and spinel crystals and rare grass green diopside grains. Clinopyroxene oikocryst with ophitic texture in plagioclase altered to clay xpl.