Transmitted Light
PYROXENES:
Monoclínic (clinopyroxenes):
Diopsíde (PPL: colorless to pale green, weak pleochroism)
Hedenbergite (very similar to diopside)
Augite (very similar to diopside)
Pigeonite (very similar to diopside)
Omphacite (very similar to diopside)
Jadeite (very similar to diopside)
Aegirine (PPL: pleochroism between green and yellowish-brown)
Orthorhombic (orthopyroxenes):
Enstatite – Ferrosilite: colorless or weakly pleochroic in pinkish or reddish. Paralell extinction, ES(+).
(Hipersthene and Bronzite are discredited names).
CARBONATES:
Calcite (PPL: colorless, relief changes with the turn of the stage (“chagrín change” or “relief pleochroism”), usually anhedral. XPL: white-pearly, twins common; CL: U(-), but may show 2V of 0-15º.
or may be dolomite or siderite or magnesite or rhodocrosite.
It is not possible to distinguish these carbonates from each other under the petrographic microscope, other analytical techniques are needed.
ANDALUSITE:
PPL: colorless, medium relief.
XPL: gray, paralell extinction, in longitudinal sections ES(-), B(-).
KORNERUPINE:
PPL: colorless, high relief.
XPL: paralell extinction, gray to yellow, ES(-).
Very rare mineral.
RHODONITE:
PPL: colorless, high relief.
XPL: gray, white or yellow, oblique extinction, B(+).
Rare mineral.
AMPHIBOLES:
Actinolite (PPL: colorless/pale green, weak pleochroism)
Tremolite (PPL: colorless)
Cummingtonite (PPL: colorless or weak pleochroism).
Antophyllite (PPL: usually colorless; CPL: colorful).
Green hornblende (PPL: green. Strong pleochroism).
Brown hornblende (PPL: brown. Strong pleochroism).
Arfvedsonite (PPL: deep colors and strong pleochroism).
Glaucophane (PPL: blue, with strong pleochroism).
Riebeckite (PPL: deep blue, strong pleochroism).
KYANITE:
PPL: colorless, high relief.
XPL: gray to weak yellow. ES(+), B(-). Common in pelitic metamorphic rocks.
WOLLASTONITE:
PPL: colorless, medium/high relief.
XPL: extinction 0-5 degrees, ES(+/-), B(-). Occurs in marbles.
SCAPOLITE:
PPL: colorless, low/medium relief.
XPL: paralell extinction, ES(-), U(-).
Very rare mineral.
CORUNDUM:
PPL: two good partitions, colorless, high relief.
XPL: gray or white, paralell extinction.
Rare mineral.