The most commonly known mineral that can be scratched with a fingernail is talc.
Talc is a very soft mineral, ranking as 1 on the Mohs scale of hardness, and your fingernail is harder at around 2.5. This means your fingernail can easily scratch talc due to the difference in hardness levels.
When you scratch a mineral with a penny, nail, and your fingernail, you are testing the mineral's hardness. The ability to scratch or be scratched by certain materials helps determine the mineral's hardness on the Mohs scale of mineral hardness.
Your nail is 2.5 so the rocks you can scratch are, Gypsum and Talc.
GypsumHardnessMineralAssociations and Uses1Talc (Softest)Talcum powder. (can be scratched by a fingernail.)2GypsumPlaster of paris.Gypsum is formed when seawater evaporates from the Earth's surface. (May be scratched by a fingernail or by a copper coin.)3CalciteLimestone and most shells contain calcite.(Can be scratched by a steel pocket knife or sometimes a copper coin. Will scratch a fingernail, may scratch a copper coin.)4FluoriteFluorine in fluorite prevents tooth decay.(Can be scratched by a steel pocket knife. Will scratch a fingernail and a copper coin.)5ApatiteWhen you are hungry you have a big "appetite".(Can be scratched by a steel pocket knife. Will scratch a fingernail and a copper coin.)6OrthoclaseOrthoclase is a feldspar, and in German, "feld" means "field".(Will not scratch glass but will scratch steel blades, copper coins & fingernails.)7Quartz (Will scratch glass, steel blades, copper coins & fingernails.)8TopazThe November birthstone. Emerald and aquamarine are varieties of beryl with a hardness of 8. (Will scratch glass, steel blades, copper coins & fingernails.)9CorundumSapphire and ruby are varieties of corundum. Twice as hard as topaz.(Will scratch glass, steel blades, copper coins & fingernails.)10Diamond (hardest)Used in jewelry and cutting tools. Four times as hard as corundum.(Will scratch all of the above.)
According to Moh's Hardness scale, you can scratch a mineral with your fingernail if it has a hardness of 2.5 or less. Calcite has a hardness of 3, meaning that you cannot scratch it with your fingernail.
you can scratch talc becuase it is the softest mineral on the moth scale.
Talc is a very soft mineral, ranking as 1 on the Mohs scale of hardness, and your fingernail is harder at around 2.5. This means your fingernail can easily scratch talc due to the difference in hardness levels.
When you scratch a mineral with a penny, nail, and your fingernail, you are testing the mineral's hardness. The ability to scratch or be scratched by certain materials helps determine the mineral's hardness on the Mohs scale of mineral hardness.
The mineral that you can't scratch with your fingernail but can be scratched by a copper penny is calcite. Calcite has a hardness of about 3 on the Mohs scale, while fingernails have a hardness of around 2.5. A copper penny, which has a hardness of approximately 3.5, can easily scratch calcite.
A mineral's hardness can be determined using a fingernail, penny, or nail by testing its ability to scratch or be scratched by these objects. The Mohs scale of hardness ranks minerals from 1 (talc) to 10 (diamond), with a fingernail typically rated at 2.5, a penny at about 3.5, and a nail around 5.5. By attempting to scratch the mineral with these items, you can estimate its hardness based on which objects can scratch it and which cannot.
If a fingernail can scratch a mineral, you are testing the mineral's hardness. Hardness is a measure of a mineral's resistance to being scratched by other materials. Minerals are ranked on the Mohs scale of hardness from 1 (softest) to 10 (hardest).
The Mohs hardness of serpentine is 2,5-3; it a soft mineral. Not scrached by a graphite pen; scratched by fingernail, copper etc.
Your nail is 2.5 so the rocks you can scratch are, Gypsum and Talc.
Mineral hardness is tested on a glass plate or usually a finger nail.
Kaolin is a soft white clay used in making porcelain. You can scratch kaolin with your fingernail, so, because diamond is the hardest known mineral, of course a diamond will also scratch kaolin.
It would depend on how loosely the sandstone was cemented. Some sandstone can be crumbled in your clenched fist, and some are extremely hard.
GypsumHardnessMineralAssociations and Uses1Talc (Softest)Talcum powder. (can be scratched by a fingernail.)2GypsumPlaster of paris.Gypsum is formed when seawater evaporates from the Earth's surface. (May be scratched by a fingernail or by a copper coin.)3CalciteLimestone and most shells contain calcite.(Can be scratched by a steel pocket knife or sometimes a copper coin. Will scratch a fingernail, may scratch a copper coin.)4FluoriteFluorine in fluorite prevents tooth decay.(Can be scratched by a steel pocket knife. Will scratch a fingernail and a copper coin.)5ApatiteWhen you are hungry you have a big "appetite".(Can be scratched by a steel pocket knife. Will scratch a fingernail and a copper coin.)6OrthoclaseOrthoclase is a feldspar, and in German, "feld" means "field".(Will not scratch glass but will scratch steel blades, copper coins & fingernails.)7Quartz (Will scratch glass, steel blades, copper coins & fingernails.)8TopazThe November birthstone. Emerald and aquamarine are varieties of beryl with a hardness of 8. (Will scratch glass, steel blades, copper coins & fingernails.)9CorundumSapphire and ruby are varieties of corundum. Twice as hard as topaz.(Will scratch glass, steel blades, copper coins & fingernails.)10Diamond (hardest)Used in jewelry and cutting tools. Four times as hard as corundum.(Will scratch all of the above.)