The simplest way to make a powder is to grind the mineral on a small rectangular piece of unglazed ceramic called a streak plate. Streak plates have a Mohs hardness around 7, but be sure to check your streak plate against a piece of quartz (hardness 7) because some are softer and some harder. The streak plates shown here have a hardness of 7.5. An old kitchen tile or even a sidewalk can also serve as a streak plate. Mineral streaks can usually be wiped off easily with a fingertip.
|Streak Plates||The Typical White Streak||Beware of Scratches||Identifying Native Metals by Streak|
|Cinnabar and Hematite Streaks||Identifying Galena by Streak||Identifying Magnetite by Streak||Streak of Copper Sulfide Minerals|
|Goethite and Hematite Streaks|
- Graphic Index
- Text Index