The ore microscope is the basic instrument for the petrographic examination of the large and economically important group of minerals referred to collectively as "ore" or "opaque" minerals. Although neither term is strictly correct (inasmuch as pyrite is opaque but rarely, if ever, constitutes an economically viable ore and sphalerite and cassiterite are important ore minerals but are not opaque), both terms are frequently used synonymously.

The recognition and interpretation of ore textures is a difficult task, and the problem is compounded firstly by the relatively low priority given to the subject within most tertiary training institutions, and secondly by the lack of simple well illustrated texts. Special reference needs to be focused upon features which are visible to the eye or observed via a hand lens. These are the most valuable to practicing field geologists. <...>

It is often assumed that when China becomes aroused to the need of equipping herself with the tools and technique of America and Europe, there will be a great and rapid industrial and commercial advance comparable with that of England, Germany, and the United States during the last century. Her supposed untold wealth, in uvast resources” of raw materials and man power, when organized, is to produce, we are told, both the fiercest industrial competition the world has ever seen and the greatest potential market. The Industrial Revolution of the West, it is forebodingly asserted, is only the curtain-raiser for the vaster drama of the twentieth century to be played in Asia, where “the stage seems set for catastrophe.”

Each of the following pages contains a protractor for a specific size of drill core. 

Choose the appropriate chart for the drill core size. Check the core diameter to choose the appropriate template within each core size grouping.

The protractors are in two groups: beta angle protractors and alpha/beta angle protractors. In practice I find that the beta angle protractor alone is best as it is least cluttered with lines (and alpha angles are easily measured using a protractor). <...>