question: Measuring hardness of minerals requires a harder what?
choices.text: calcium as a base cartilage mineral stoma osculum the same weater
choices.label: A B C D E F G H
fact2: Harder minerals can scratch softer minerals.
combinedfact: Measuring hardness of minerals requires a harder mineral.
formatted_question: 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