John investigated the properties of two minerals and recorded his observations:
Feldspar is a gray, dull, solid that has flat surfaces.
Calcite is a white, dull, solid that has flat surfaces.
What evidence could John use to conclude that both minerals are non-metallic?
Both minerals are dull.
Both minerals are solids.
Both minerals have flat surfaces.
Feldspar is gray, while calcite is white.