The streak plate method is a way to physically separate the microbial population, and is done by spreading the inoculate back and forth with an inoculating loop over the solid agar plate.
12.
In case of harder minerals, the color of the powder can be determined by filing or crushing with a hammer a small sample, which is then usually rubbed on a streak plate.
13.
Because the trail left behind results from the mineral being crushed into powder, a streak can only be made of minerals softer than the streak plate, around 7 on the Mohs scale of mineral hardness.
14.
For example, conventional plating would require preparing agar for pour plating, or using agar plates and vial inoculum loops for streak plating; but for Petrifilm plates, the agar is completely housed in a single unit so that only the sample has to be added, which saves time.
15.
I do not have equipment to find its specific gravity, but with porcelain streak plate ( which I use bottom of my porcelain crucible ) it did produce black streak, the picture of it can be viewed at my blog . So, does this confirm the material I have is sperrylite ? Preceding talk ) 13 : 24, 24 March 2011 ( UTC)
