Tag: Rock identification

Iron is the fourth most abundant element in the Earth's crust, but does this mean all stones are rich in iron? The simple answer is no; most rocks only contain trace amounts, while significant quantities are concentrated in specific iron ore formations.

Over 4,000 distinct mineral types have been identified and formally recognized by the International Mineralogical Association. Understanding the key points of minerals—their definitive characteristics, formation, and classification—is foundational knowledge for anyone studying earth science.

Less than 1% of the over 4,000 known minerals are ever considered for a taste test by trained geologists, and almost all rocks are too dangerous to lick. What rocks are safe to lick is a question with a very clear, and dangerous, answer: almost none, with a couple of specific exceptions used strictly for field identification.

Over 5,300 mineral species are recognized by the International Mineralogical Association, each possessing a set of distinct defining features. However, to answer the question, "Which one of the following is characteristic of minerals?", we must look beyond superficial traits to the fundamental criteria that classify a substance as a mineral in the first place.