question: What is required to measure the hardness of a pearl?
choices.text: lamphreys Playing with it Scratching it keratin melanin content potassium magnesium Helping it
choices.label: A B C D E F G H
fact2: Carbonate minerals, such as malachite, pearl, and rhodochrosite, are damaged by chemical attack.
combinedfact: measuring the hardness of a pearl requires scratching it
formatted_question: What is required to measure the hardness of a pearl? (A) lamphreys (B) Playing with it (C) Scratching it (D) keratin (E) melanin content (F) potassium (G) magnesium (H) Helping it