Nesosilicate · Isotropic
Garnet in thin section
Isotropic: black in XPL at every angle. High positive relief. Colorless or a pale version of the hand-sample color. No cleavage, irregular fractures, no twinning.
Plane-polarized light
| Color | Colorless, Pink |
|---|---|
| Pleochroism (color change on rotation) | None |
| Relief | High, Very high |
| Cleavage | None |
| Shape | Euhedral, Anhedral / equant |
Cross-polarized light
| Maximum birefringence | about 0.000 |
|---|---|
| Highest interference color | Black at all angles |
| Twinning | None |
Telling it apart
Spinel has a different crystal shape and darker color.
Where you'll find it
Garnet schist, gneiss, eclogite, amphibolite
Photo examples
Alex Strekeisen · Search Wikimedia Commons
Photos open on the source sites.
Identify an unknown grain Read interference colors Practice mineral ID
Related minerals
Sources
OpticMin, ATHENA, Univ. of Geneva (P. Perroud) · Alex Strekeisen thin-section collection · Distinguishing features of minerals (UT Arlington) · MIT OCW 12.109 amphibole lab · SEPM Strata: carbonate staining · Wikipedia mineral pages (infobox optical data) · Athabasca University rocks and minerals · Smith College petrography: perthite