Name: | Staurolite |
Derivation: | From "stauros lithos" (Greek) cross stone |
Formula: | (Fe,Mg)2(Al,Fe)9Si4O20(O,OH)2 |
Description: | Brown opaque crystals in a blade form (on the left of the photograph). You often get "twinning" where two crystals cross over. If this is at right angles (top right), then you get a cross shape. The bottom specimen is twinned but not at right angles. |