Latterly it has become clear that the largest progress cannot be made if the knowledge of any branch of Science is confined to a few only. The most rapid advances have been made where many men are interested and enthusiastic. In no science should there be a difficult barrier between the amateur and the professional student. All Nature is equally open for everyone to study, and there should never be created obstacles as by the use of terminology not easily acquired by anyone. Of late these barriers have been in part broken down and competent students have written guides which anyone can follow, and soon begin to know the plants, trees, birds, insects, etc. So far no one has attempted to make the study of minerals and rocks so direct and simple that everyone can get a start. Most books on minerals, and practically all those on rocks are written for school courses, and to say the least chill any enthusiasm which is naturally aroused by the finding of interesting looking rocks or minerals. The purpose of this book is first of all to provide a means of identifying minerals and rocks by such methods as are practical without elaborate equipment or previous training: and second to suggest the conditions under which the various minerals and rocks were formed, so that, at the first contact, one may get a conception of the events which have anteceded the mineral or rock which has been found. For this purpose keys have been worked out for determining the rocks and minerals by such obvious features as color, hardness, etc. Each mineral or rock is introduced by a summary of its characters, then the features by which it may be distinguished from any other similar mineral are given, after which its mode of origin and its meanings are considered. For those interested in the composition of the minerals, it is given in chemical symbols with each mineral. Most classifications of minerals are based on the composition, all the sulphides, carbonates, etc., being grouped together, but in this book, because the popular interest and commercial uses are primarily in the metal present, the minerals are grouped in each case about the chief metal, all the minerals of iron being grouped together, for instance. A few minerals and rocks which are not strictly common have been included such as gems and meteorites; the gems because they are of intense interest to their owners and are often simply perfect examples of a fairly common mineral; and such forms as meteorites because it is important that, if one should run across one, it should be recognized, and so not lost to the world. The book is freely illustrated, those minerals in which color is important for identification being illustrated in colors, and those which are black, or in which the color is not a determining factor, are shown in either photographic or outline figures.