Table of Contents
What happens when you scratch a rock?
Rock Investigation #2 | Scratch Test on Rocks If you see a scratch, a line, or dust, this means that your NAIL is HARDER than your ROCK. If you see a silver line on your rock, this means that your ROCK is HARDER than your NAIL. This is a baseline investigation.
How can you tell if a rock is hard?
As common sense dictates, Mohs Scale is based on the fact that a harder material will scratch a softer one. By using a simple scratch test, you can determine the relative hardness of an unknown mineral.
When you scratch a rock What are you testing?
Also called a scratch test, Mohs Hardness Test looks at whether or not a mineral can be scratched by another mineral. Mohs Hardness Scale has ten minerals of known hardness. You scratch your rock with each of these minerals to determine where your rock falls on the scale.
Can hardness be scratched?
Hard – cannot be scratched by a knife but can scratch glass, Mohs’ 6-9; Diamond is the hardest known mineral, Mohs’ 10.
What mineral is not scratched by a fingernail?
Mineral Hardness Test Video
| Mineral | Hardness |
|---|---|
| Calcite | |
| INTERMEDIATE Mineral cannot be scratched with a fingernail but can be scratched with a steel nail. | |
| Gypsum | |
| SOFT Mineral can be scratched with a fingernail |
Can rocks scratch glass?
Quartz is harder than any of the common minerals in meteorites. Quartz is so hard that it will easily make a deep scratch in glass. Even if you press hard, a meteorite will at best only make a weak scratch mark. (Use a sharp edge of the rock.)
What is the softest rock?
talc
The name for talc, a sheer white mineral, is derived from the Greek word talq, which means “pure.” It is the softest rock on earth.
What does schist look like?
Schist (/ʃɪst/ shist) is a medium-grained metamorphic rock showing pronounced schistosity. This means that the rock is composed of mineral grains easily seen with a low-power hand lens, oriented in such a way that the rock is easily split into thin flakes or plates.
What are 5 ways to test a rock?
Geologists use the following tests to distinguish minerals and the rocks they make: hardness, color, streak, luster, cleavage and chemical reaction.
How can I test rocks at home?
Follow this easy, step-by-step activity:
- Hardness test — Scratch the rock with a fingernail, a copper penny, a glass plate or nail, and a ceramic plate.
- Color streak test — Test for the “color streak” of the minerals by rubbing the rock across the ceramic plate in the Mineral Test Kit, or across smooth.
How do you check the hardness of a scratch?
During the scratch hardness measurement, a diamond stylus of specified geometry scratches in the surface of the tested material along a linear path under a constant normal force with a constant speed. The average width of the scratch is measured and used to calculate the scratch hardness number (HSP).
What is unit of scratch hardness?
Explanation: Scratch hardness is shown by unit Mohs. It is 10 Mohs. Talc and quartz have the hardness of 1 and 7 Mohs respectively.
What does it mean when you get a scratch on a rock?
If you see a scratch, a line, or dust, this means that your NAIL is HARDER than your ROCK. If you see a silver line on your rock, this means that your ROCK is HARDER than your NAIL. This is a baseline investigation.
What kind of rock does not have a streak?
The rock is a hematite concretion. Meteorites give no streak or a weak grayish streak, but only if you press hard. Also, any terrestrial igneous rock will not give a streak, so absence of a streak does not indicate that the rock is a meteorite.
Which is harder a mineral or streak plate?
Many minerals are harder than the streak plate. Instead of leaving a powder behind when dragged across a streak plate, they will scratch the streak plate or fracture into small pieces. Minerals that are harder than the streak plate are said to have “no streak” or a “colorless streak.”.
Can you test mineral hardness with a scratch?
Be careful not to confuse mineral powder or residue with a scratch. A scratch will be a distinct groove cut in the mineral surface, not a mark on the surface that wipes away. Use a hand lens to get a good look at what happened. Conduct the test a second time to confirm your results. A list of minerals in order of hardness can be a handy reference.