Monica found a clear mineral crystal. she wanted to identify its hardness. she tried to scratch it with her fingernail, a penny, and a steel nail but none of those worked. then she tried topaz, which did leave a scratch . the mineral was able to scratch glass. what mineral could monica have found? explain your answer.

ca has a crystalline lattice with positive ions (since it is a metal, metals are positively charged) and electrons flow freely in its structure since the ca atoms have a large nuclear radius so the electrons are not tightly held, therefore the electrons can flow freely since they are not being highly attracted by the nucleus. moreover, one of the properties of metals are that they are conductors of electricity, thus proving ca is the element.