The following is a simple illustrated guide, using calcite as an example, to help you understand!
A mineral is one of the basic building blocks of our planet. It is a naturally occurring substance that has definite physical properties and chemical composition. An example of a common mineral is Calcite. Calcite forms from sea shells, hot springs or in caves.
Related Article (using quartz as an example): Your Guide To Rock, Mineral, Crystal
A rock is composed of one or more minerals. Rocks are literally the foundation of our planet. A rounded piece of rock is often referred to as a stone. Marble is formed from limestone by heat and pressure within the Earth. Marble is composed primarily of calcite or dolomite minerals.
A crystal is a mineral that forms under ideal conditions. It is like a child raised in the perfect family! Every crystal has it own unique angular shape that sets it apart from other crystals. The conditions under which crystals form contribute to their healing properties.
A valuable rock or mineral. Generally it has been cut and polished for use in jewelry. Sometimes a gemstone refers to a beautiful crystal even if it is not intended for commercial use. This beautiful calcite gemstone is ready for use in a ring or necklace!