PETROGRAPHIC CHARACTERISTICS
OF UNKNOWN #4
| MATERIAL NAME |
|
| HABIT |
Fibrous - straight to curved |
| COLOR AND PLEOCHROISM |
Usually dark brown but can vary
|
| APPROXIMATE
R.I. VALUE |
Closest to 1.55 |
| INTERFERENCE COLORS |
Moderate |
| EXTINCTION |
Parallel |
|
ADDITIONAL DESCRIPTIVE FEATURES |
Usually contains a central channel (may be discontinuous) and a scaley texture on the surface. Tip often tapers. |
| KEY DIAGNOSTIC FEATURES |
Inner channel and scaley texture |