You can not see between opaque materials because light cannot pass through them.
Magnesium would be more reactive.
I think the mineral characteristics that the one gram sample of hematite taking up more space than a one gram sample of malachite is DENSITY.
The density of hematite is 5.26 g/cm³
The density of malachite is 3.6 to 4 g/cm³
Other physical characteristics of minerals are <span><span>Color, </span>Streak, Luster, H<span>ardness, </span>Cleavage, Fracture, Tenacity, and Crystal <span>Habit.</span></span>
1) 100s of millions of years ago Trees and plants fall into swamps
2) Layers of rotting plant matter builds up underwater
3) Over millions of years the weight of layers heat the plant matter and turn into Peat
4) Over millions of years more pressure and heat turns Peat into coal
