Most sources define a rock as an aggregate of one or more minerals. Are there rocks that have no minerals at all?
Answer:
Yes, there are rocks with no minerals. Minerals must be inorganic, never part of a living thing. Rocks that are made up of pieces of living things are not made of minerals. That includes things such as coal (plant material), coquina (sea shells), and as seen in the photo above, chalk (foraminifera).
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