For this reason, Chang'e 4 will study the effect of solar winds on the lunar surface and any mineral found by the spacecraft.

Since all forms of potassium alum are soluble in water, when the stone is wet or applied to wet skin, an invisible, fine layer of the mineral is rubbed off the stone and applied to the skins surface.

There are natural cotton crystal, mineral, concave surface, the natural normal function of any minor damage, is not a quality problem.