20 green calcite mineral specimens perfect for your rock tumbler Green calcite belongs to the mineral class of carbonate and is formed through sedimentation. The color green in the stone comes from the chlorite that got trapped during crystallization. It has a soothing and beautiful light green shade, and the stone is opaque that looks a lot like washed sea glass. according to metaphysics, Green-Calcite will be with you in your journey of self-discovery. It will show you how you can accept yourself wholly and embrace all your imperfections. Once tumble, they become a magnificent looking gem stone that’s perfect for jewelry, crafts or just to admire.