PETROGRAPHIC CHARACTERISTICS
OF UNKNOWN #3
| MATERIAL NAME |
|
| HABIT |
Fibrous - Straight to curved |
| COLOR AND PLEOCHROISM | Dark Blue Pleochroic from darker to lighter shades of blue |
| APPROXIMATE
R.I. VALUE |
1.68 |
| INTERFERENCE COLORS |
Anomalous |
| EXTINCTION |
Inclined: Angle = 10 degrees |
|
ADDITIONAL DESCRIPTIVE FEATURES |
The interference colors are anomalous (i.e., they do not correspond to colors on the standard color chart). The anomalous blue to purple-brown interference colors result from the intense color of the mineral |
| KEY DIAGNOSTIC FEATURES |
Blue color, anomalous interference |