Geophagia or more commonly called soil eating is quite common in most species, and has been seen in both wild and domesticated horse breeds. Often this is seen as an indicator of a nutritional deficiency in the diet or in other cases boredom. Based upon studies of the soils that various species consume, several theories have been developed about various soil components that may stimulate geophagia. This study examined the chemical components of the soil from 13 different locations in Australia where geophagia has been observed. The soil from the sites where geophagia took place has significantly higher concentrations of iron and copper, when compared to control soil samples. Hence, it may the iron and copper that stimulates geophagia in horses.