A Mineral Hardness Kit is made up of reference rocks and mineral samples and a scratching tool. Test Kits will often contain with (9) specimens: gypsum, talc, calcite, fluorite, apatite, orthoclase, quartz, topaz and corundum. Use will use a nail or scratching tool to see if you can scratch any of the minerals in the box you purchased. Based on whether or not the nail leaves a mark on the sample or not gives you a related indication of the mineral hardness in the kit.
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Kit of Mohs’ Hardness Mineral Identification
https://en.wikipedia.org/wiki/Mohs_scale_of_mineral_hardness