Measuring hardness of minerals requires a harder what?
calcium as a base cartilage mineral stoma osculum the same weater
A B C D E F G H
Harder minerals can scratch softer minerals.
Measuring hardness of minerals requires a harder mineral.
Measuring hardness of minerals requires a harder what? (A) calcium (B) as a base (C) cartilage (D) mineral (E) stoma (F) osculum (G) the same (H) weater