If you are talking about the side effects of taking in certain minerals, there is no dearth of examples that can be provided. But if you are referring to the kind of minerals that are applied to the surface of the skin, then the story changes altogether. These are different and they would not really have any serious side effects unless you would become what would be known as abusive to them. For instance if you are taking some sort of mineral based treatment in order to reduce the darkness of your skin or to add to or take away from the oil quotient of the skin, this would normally not have any side effects unless you happen to be allergic to the substances. It would also be pretty difficult to abuse these things. If you end up applying excessive amounts in any case, in all likelihood, your skin will reject the stuff and it will just sit there on the surface. If we are talking about an excess of minerals that you would take into your body, this would indicate not only intake but also intravenous injection. In most cases, if the latter has happened, it could actually end up being fatal to the person who has been injected.
In case of consumption, you would have to look at each individual mineral to see what side effect an excessive intake of it could possibly result in. It is possible that there may be mild side effects if the mineral is consumed in a bit of excess, but if it is consumed in large quantities, it could also result in the person affected going into a coma. Things like vomiting and diarrhea are the first normal and usual signs that the body has taken more quantities than it can handle. In all likelihood, the body would manage to eject the harmful quantities of the substance you may have taken. But if not, then it can enter your bloodstream, which can become a potential fatal hazard. Different minerals when taken in excess have different results. You can be in the danger of slipping into a coma, having grand mal seizures, become paralytic, developing permanent problems such as loss of muscle control and function, or, finally, dying altogether. Some of the side effects can also include changes in skin color or vision efficiency. You are advised to contact a poison control center instantly if you suspect any excessive mineral intake.