The streak test should be done on clean, unweathered, or freshly broken specimens of the mineral. This is done to reduce the possibility that a contaminant, weathered coating, or tarnish will influence the results of the test.
The preferred method for conducting a streak test is to pick up a representative specimen of the mineral with the hand that you write with. Select a representative point or protrusion on the specimen that will be scraped across the streak plate. With your other hand, place the streak plate flat on a tabletop or laboratory bench. Then, while holding the streak plate flat and firmly in place on the tabletop, place the point of the specimen firmly against the streak plate, and, while maintaining firm pressure, drag the specimen across the plate. Now examine the streak to determine its color and to confirm that it is a powder, instead of grains, splinters, or broken pieces.
| Streak Colors of Common Minerals | |
| Andalusite | White or colorless (hardness is about the same as the streak plate). |
| Anhydrite | White. |
| Apatite | White. |
| Arsenopyrite | Dark grayish black. |
| Augite | White to greenish gray. Augite can be splintery and close to the hardness of the streak plate, so brittle fragments, rather than a powder, will sometimes be produced. |
| Azurite | Light blue. |
| Barite | White. |
| Bauxite | White. Often discolored to pink, brown, or red by iron staining. |
| Benitoite | White. |
| Beryl | Colorless (harder than the streak plate). |
| Biotite | White to gray (don’t be deceived by flakes). |
| Bornite | Grayish black. |
| Calcite | White. |
| Cassiterite | Colorless. |
| Chalcocite | Grayish black. |
| Chalcopyrite | Greenish black. |
| Chlorite | Greenish to greenish-black to white. |
| Chromite | Dark brown. |
| Chrysoberyl | Colorless (harder than the streak plate). |
| Cinnabar | Red. |
| Clinozoisite | White. |
| Copper | Metallic copper red. |
| Cordierite | Colorless (harder than the streak plate). |
| Corundum | Colorless (harder than the streak plate). |
| Cuprite | Brownish red. |
| Diamond | Colorless (harder than the streak plate). |
| Diopside | White to light green. |
| Dolomite | White. |
| Enstatite | White to gray. |
| Epidote | White or colorless (about the same hardness as the streak plate). |
| Euclase | White or colorless (when harder than the streak plate). |
| Fluorite | White. |
| Fuchsite | White (often sheds tiny green mica flakes). |
| Galena | Lead gray to black. |
| Garnet | Colorless (harder than the streak plate). |
| Glauconite | Dull green. |
| Gold | Metallic gold yellow. |
| Graphite | Black. |
| Gypsum | White. |
| Halite | White. |
| Hematite | Red to reddish brown. |
| Hornblende | White. Brittle, often leaves black cleavage debris behind instead of a streak. |
| Ilmenite | Black. |
| Jadeite | Colorless (harder than the streak plate). |
| Kyanite | White or colorless (about the same hardness as the streak plate in one direction). |
| Limonite | Yellowish brown. |
| Magnesite | White. |
| Magnetite | Black. |
| Malachite | Green. |
| Marcasite | Grayish Black. |
| Molybdenite | Bluish gray, gray. |
| Monazite | White. |
| Muscovite | White, often sheds tiny cleavage flakes. |
| Nepheline | White. |
| Nephrite | Colorless (harder than the streak plate). |
| Olivine | White or colorless (about the same hardness as the streak plate). Often sheds tiny granules instead of a powder. |
| Orthoclase | White. |
| Plagioclase | White. |
| Prehnite | White. |
| Pyrite | Greenish black to brownish black. |
| Pyrophyllite | White. |
| Pyrrhotite | Grayish black. |
| Quartz | Colorless (harder than the streak plate). |
| Rhodochrosite | White. |
| Rhodonite | White. |
| Rutile | Pale brown. |
| Scapolite | White. |
| Serpentine | White. |
| Siderite | White, very light brown. |
| Sillimanite | White or colorless (about the same hardness as the streak plate). |
| Silver | Silvery white. |
| Sodalite | White or light blue. |
| Sphalerite | White to yellowish brown, often with an odor of sulfur. |
| Spinel | Colorless (harder than the streak plate). |
| Spodumene | White or colorless (about the same hardness as the streak plate). |
| Staurolite | Colorless (harder than the streak plate). |
| Sulfur | Yellow. |
| Sylvite | White. |
| Talc | White to pale green. |
| Titanite | White. |
| Topaz | Colorless (harder than the streak plate). |
| Tourmaline | Colorless (harder than the streak plate). Specimens often fracture, shedding small particles. |
| Turquoise | White, greenish, bluish. |
| Uraninite | Brownish black, grayish. |
| Vanadinite | Pale yellow to yellowish brown. |
| Witherite | White. |
| Wollastonite | White. |
| Zircon | Colorless (harder than the streak plate). |
| Zoisite | White. |