Streak Test of a Mineral
Web-Science.net
What is streak?
Streak is the color of the powdered mineral left on the surface of the streak plate.
How do we test the streak?
Using a streak plate made of unglazed porcelain tile, rub the mineral across the
surface of the plate. The streak plate has a hardness of about 7. If the mineral is
as hard or softer, it will leave its streak (fine powder) on the surface. The color of
the streak is one variable in helping to identify the mineral.
Where is streak most useful in identification?
It is most useful for metallic minerals. Metallic minerals show a streak of different
colors. Non-metallic minerals, even when colored, generally give a white powder,
therefore, a white streak.
Streak is the color of the powdered mineral left on the surface of the streak plate.
How do we test the streak?
Using a streak plate made of unglazed porcelain tile, rub the mineral across the
surface of the plate. The streak plate has a hardness of about 7. If the mineral is
as hard or softer, it will leave its streak (fine powder) on the surface. The color of
the streak is one variable in helping to identify the mineral.
Where is streak most useful in identification?
It is most useful for metallic minerals. Metallic minerals show a streak of different
colors. Non-metallic minerals, even when colored, generally give a white powder,
therefore, a white streak.
Mineralogical Society of America's guide with streak of
many minerals:
Non-metallic luster, definite streak
many minerals:
Non-metallic luster, definite streak