Staurolite is a dull and generally pitted.

Chemical Formula: (Fe,Mg,Zn)2Al9(Si,Al)4O22(OH)2
Class: Alumino-silicate
Hardness: 7-7.5
Coloration: Brown to near black

How to identify it/Unique Characteristics or Properties: Staurolite is a dull and generally pitted looking crystal that is named after the Greek word for cross, “stauros”. This crystal has a definite affinity for twinning, where duplicate crystals grow through each other and form one crystal. In staurolite, almost a third of the crystals come twinned, either with the crystals at 60 degree angles to each other, or perpendicular, forming the shape of a cross. The picture above is of one that is twinned perpendicular. Pictured below is one that is twinned at 60 degrees and a perpendicular one that is just barely formed (look for the ridges).

Where to find it in…

The Northwest: N/A
Other: Georgia, New Mexico USA. France, Brazil.
Past Uses: Because it can naturally look like a cross, staurolite took on a mythic nature and was sometimes used as a good luck charm in past times.
How it was Made: Staurolite forms in deep metamorphic, aluminum rich rock when it goes under pressure.
Interesting Facts: Staurolite is quite hard and when the minerals around it eroded, leaving a cross, it definitely left an impact on medieval Christians.