Staurolite
Big Photo Staurolite is named from Greek "stauros" - a cross, alluding to the cruciform twins (fairy crosses) it displays in some cases.
Staurolite forms characteristic monoclinic, pseudo-orthorhombic prismatic, reddish brown crystals, often forming 60° twins. The crystals are mostly translucent, rarely transparent. Staurolite shows distinct pleochroism - colourless - yellow - reddish brown.
Rouch material to facet brilliant gems is very rare.