A streak plate is a surface of unglazed ceramic, used to find the true color of a mineral specimen by drawing the specimen across it. The color of the resultant powder is referred to as the streak or streak color of a mineral.
The purpose of using a streak plate in microbiology experiments is to isolate and separate individual bacterial colonies for further study and identification.
In scientific circles, the streak plate method is considered to be a rapid qualitative isolation method. To be effective, one must reduce the number of organisms in the inoculums by spreading a loop of culture over an agar plate. This ensures that individual cells are properly separated on the surface for the purpose of differentiating various species. The method is as follows: Using a sterile loop, microbes are initially transferred to the plate with one swipe. On the subsequent swipes, the loop is heated in the flame of a Bunsen burner to lessen the population of microbes being transmitted. Streak patterns are also done in via T-streak or by applying the loop to four quadrants of the plate.
A streak plate technique is used to isolate individual bacterial colonies on a solid agar plate to obtain pure cultures, while a serial dilution technique is used to dilute a bacterial sample in a series of steps to obtain a range of concentrations for further analysis. Streak plate technique is qualitative, focusing on colony isolation, while serial dilution technique is quantitative, focusing on estimating bacterial concentration.
A streak plate with two species of bacteria will show separate colonies with distinct morphologies and colors. Each species will grow in its own isolated area on the plate, allowing for differentiation between them. It is important to observe and document the characteristics of each colony to identify and classify the bacteria present.
Bacterial mixture is transferred to the edge of an agar plate with an inoculating loop and then streaked out in one of several patterns. At some point, individual cells will be removed from the loop and will give rise to separate colonies.source: http://quizlet.com/17578430/micro-lab-unit-1ex-15-16-streak-plate-technique-flash-cards/
A streak plate is used to determine the streak colour of a mineral. You take the mineral and scratch it against the streak plate, and it will create a coloured streak on the plate. The streak is not always the same colour as the mineral itself.
The lack of a streak would indicate that the mineral is harder than the streak plate, or the color of the streak is the same as the color of the streak plate.
Diamond will not leave a streak on a porcelain streak plate because diamond is harder than the streak plate. It will leave a scratch on the streak plate for the same reason.
I do not have a picture, but when you scratch aquamarine on a streak plate, the powder will be white colored.
Two minerals that do not leave a streak on a streak plate are quartz and fluorite. Both minerals have a hardness higher than that of the streak plate, so they will not leave a streak when rubbed against it.
You can determine the streak of a mineral whose Mohs scale is higher than the streak plate by either filing or crushing with a hammer before rubbing the sample on a streak plate.
The powder left behind on a streak plate is called a streak. It is produced by scraping a mineral sample across the plate to reveal its color and texture. This streak can be compared to a mineral's known streak color to help with identification.
It leaves a scratch instead of a streak because Topaz has a higher number on the Moh's scale compared to the streak plate.
Topaz (8), corundum (9), and diamond (10).
Diamond is the only mineral that can scratch glass but not leave a streak on a streak plate. Glass has a hardness of around 5.5 on the Mohs scale, while a streak plate typically has a hardness of around 6.5. Diamond, with a hardness of 10, is able to scratch glass but not the streak plate.
Those minerals that are harder than the unglazed porcelain streak plate will scratch it rather than leave a streak.
The streak left on the streak plate by rubbing a pumice rock usually appears white or colorless. This is because pumice is a light-colored rock composed of volcanic glass with a frothy texture due to gas bubbles trapped in the rock, causing it to create a light streak when rubbed on a streak plate.