The Earth star chakra anchors us strongly to the Earth. It makes us grounded! The stones that are black in colour, mostly work on the Earth star chakra, like black tourmaline, smoky quartz and black obsidian. Iron also strongly connects to the Earth star chakra.
When we connect with this chakra, we may feel the body getting more strengthened with the elemental energy of Earth. It also brings up deeper issues (emotional/physical) for us to face and heal. If the heart chakra and the higher chakras are open enough, one could bravely face those issues.. It is our own garbage and we have to face it sometime and heal! :) When we work with this chakra, we also connect with the collective consciousness. When we heal our personal issues, we shall be able to become better anchors of light. Opening up the Soul star and the Earth star chakras shall make us wonderful pillars of light..
If the earth element dominates, it may even constipate the physical body (this happens easily if the water element in the environment is less - warm regions; it is easier to feel earth on warm days). It would be wonderful to balance the earth element with water element. I prefer copper for that. Stones like moonstone and amethyst also would help with their water element. Water keeps everything flowing! If it gets too difficult to handle, take off grounding stones. When you are prepared enough, bravely wear it again! ha ha.. Have fun!