From the introduction:
The edraldi race have long been a part of rural life in the Empire of Splendour. They are an ancient race with mysterious ties to the fertility of the land. To have edraldi nearby means that fields will be more productive, mines will yield more ore, earthquakes will be less frequent and wild woods will be wilder. At least, that’s how the stories go. One strange facet of the edraldi race, not commonly known to outsiders, is that they have four sub-types – earth, stone, metal and gem. The edraldi reproduce by rituals, requiring one of each of these sub-types, and the new edraldi grows fully-formed, physically and mentally, from the ground.