Two students were hunting for rocks and minerals to take to science class to identify. They were going to use the properties of rocks and minerals to help with the identification. They noticed that the rock shown in the image has luster. That means it must contain a mineral that is a metalloid, non-metal, hy metal D rare earth element. Please help!!

10 years is the answer

i believe the answer is true.

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.