That depends what you scratch it with, what material the rock is made from, and how much force you apply when scratching.
you can crush it good or you can scratch it on something hard
No, you generally cannot scratch shale with your fingernails. Shale is a sedimentary rock that is relatively hard and composed of clay minerals, making it more resistant to scratching. Fingernails have a hardness of about 2.5 on the Mohs scale, while shale typically has a hardness of around 3 to 4. Therefore, a fingernail would not be able to leave a scratch on shale.
When the hard parts of an organism decay and leave a cavity in the rock, a fossil mold can form. This mold is a negative impression of the organism's hard parts in the surrounding rock, preserving the shape and structure of the original organism.
Weather and erosion only mark a rock. They leave lines /patterns and eventualy work into it.
TourmalineCorundumDiamond
no
The hardness of a rock is typically described using the Mohs scale of mineral hardness, which ranks minerals from 1 to 10 based on their ability to scratch one another. For example, talc is rated as 1 (very soft), while diamond ranks as 10 (extremely hard). Additionally, hardness can be assessed through tests like the scratch test, where a harder material can scratch a softer one. In practical terms, a rock's hardness affects its durability and suitability for various uses, such as construction or jewelry.
Magnetite is considered to be a hard mineral, not a rock, because it has the ability to scratch glass and its hardness number is greater than 5.5 according to the Mohs scale.
TourmalineCorundumDiamond
If two rocks cannot scratch each other, then they would have to be of equal hardness. A harder rock can always scratch a softer rock.
When you scratch a rock on something, it’s often referred to as testing the rock's hardness or conducting a scratch test. This is commonly done to identify minerals using the Mohs scale of mineral hardness, which ranks minerals based on their ability to scratch one another. The process can help determine the composition and characteristics of the rock or mineral being tested.
it can get scratch by a diamond