1942: Mineralogy

The first year of active participation of the United States in the Second World War was marked by a noticeable drop in the volume of papers published on mineralogical subjects in the United States. At the same time the inflow of mineralogical journals from other countries almost ceased, so that little can be reported concerning the contributions made by men working in other lands.

However, there are many signs that the mineralogists are more active than ever before. One evidence of this is the announcement of discoveries of sorely needed minerals. For example, during the current year announcements have been made of the finding of beryllium ore in New Mexico, and carnallite, a potash salt, in Utah. A considerable number of mineralogists have been searching for magnesium minerals, so that our rapidly growing production of magnesium metal may be increased. This search has been singularly successful.

Axis conquests during the last year have made necessary an intensified search for essential minerals in the Western Hemisphere. A little over a year ago the chromite deposits of the Philippines were being extensively surveyed; now North and South America are being searched for commercial deposits of this and other valuable metals. During 1942, bulletins were published by the United States Geological Survey on chromite deposits in Alaska, magnesium resources in the state of Washington, and quicksilver deposits in Arkansas.

Another current activity of mineralogists is in the field of synthetic gem stones. Great strides have been made in this country in the manufacture of synthetic gems since the cessation of imports from foreign countries, especially Germany. These stones are not being made for purposes of adornment, but for bearings in precision instruments. Most of the synthetic gems being manufactured at the present time in the United States are made of alumina. Natural alumina is the mineral corundum, which is better known to the public by its gem names ruby and sapphire. Synthetic emeralds (the mineral beryl) have been made for the first time in the United States during recent months.

The address of the president of the Mineralogical Society of America, given at the annual meeting in late December 1941, dealt with the development of such instruments as the polarizing microscope, the reflecting goniometer, and the X-ray, and the role played by these ingenious tools in the evolution of the science of mineralogy. The annual meeting for 1942 was cancelled.

An unusual feature of the last convention of mineralogists was a symposium on diamonds. The diamond is playing such an important role in modern industrial life that this symposium was extremely timely. The papers covered such topics as the production of diamonds throughout the world, methods of cutting, the use of diamonds in wire drawing, the drilling of diamond dies, diamond set tools, bonded diamond wheels, and criteria for the evaluation of diamonds. Immediately after war broke out in Europe diamond cutting in the United States grew from an infant industry into a large and important one.

A large and active group of mineralogists continues to be interested in meteorites. No new falls of note were recorded during the year. The internal structure of crystals as determined by X-ray photographs also attracts many research workers. An 'Introduction to X-ray Crystallography,' a textbook in this general field, was published by an American investigator during the year.

Chemical analysis of minerals is so laborious and time-consuming that mineralogists utilize other methods of analysis wherever possible. The spectrograph is being used to an increasing extent, especially to determine minor chemical constituents. Because of its relative ease in application, one investigator reporting during the year recommended spectrographic analysis as an aid in correlating igneous rocks. Another ingenious method of analysis, which avoids actual chemical assay, was described in a paper published late in the current year. The behavior of the different clay minerals while undergoing heating has been determined; therefore, a clay of unknown composition can be treated in the same manner, and the materials present determined by a study of the thermal curves obtained.

The development of these short cuts does not mean that chemical mineralogy is no longer an active field of research. Two mineralogical chemists published a paper during 1942 on the alkali metals occurring in the various minerals of the mica group. In all, forty-three different samples of micas were analyzed for the lithium, sodium, potassium, rubidium, and caesium content. Lithium was found to be present in every mica analyzed, as, of course, were sodium and potassium. Rubidium and caesium were less common. Another use of chemical mineralogy is in determining the ratio between lead, uranium, and thorium so as to determine the age of minerals. Analyses of uraninite from Spruce Pine, North Carolina, show that it is approximately 380,000,000 years old.

The study of rocks and their origins advances in widely scattered parts of the globe. A paper was published in a British journal describing a series of unusual volcanic rocks from Southwest Uganda. A German periodical contained an article on the regional petrography of rocks in the mountains of central Europe. A systematic study of the heavy minerals contained in a dike rock in Rhode Island showed that the proportion of these heavy minerals increases systematically between the top and base of the dike. Another writer described the alkaline carbonate intrusives near Bancroft, Ontario, and expressed his opinion that the presence of alkaline and carbonate minerals in these rocks can be explained best by postulating reaction between granite magma and limestone rocks. For the first time the mineralogically interesting pegmatites of the Custer Area in the southern Black Hills of South Dakota were described in considerable detail. The growing tendency on the part of the many students of granites to ascribe the origin of this rock to a recrystallization of pre-existing sedimentary rocks was countered by an American investigator who presented strong evidence that such granitization could not take place without the addition of magmatic fluid.

At least two papers appeared during the year on the application of mineralogy to problems of sedimentation. One of these involved a study of the heavy minerals in sand now being deposited on the beaches of the Texas Gulf coast. It was found that each of the principal rivers emptying into the sea off Texas carries a distinct suite of these heavy minerals; therefore, by studying the beach sands it is possible to determine the source rivers and the direction of the longshore currents distributing the sediment. The other paper counters a tendency on the part of some sedimentologists to ascribe the elongation of quartz grains in sands as due to fracture and abrasion during transport. The authors carried out a set of experiments on quartz from which it was concluded that the characteristic elongation of these grains is due to original shape rather than to subsequent transportation.

Many papers appeared during the year in the field of applied mineralogy, or economic geology. One investigator in this branch of the science studied the crystals deposited in cavities in the lead-zinc ore bodies of southeastern Kansas and northeastern Oklahoma. He determined the direction of flow of the mineralizing solutions by noting the greater growth on the 'upstream' side of the crystals.

Ten new minerals were listed in the Journal of the Mineralogical Society of America during 1942, and during the same period four previously described species were discredited. No doubt, the greatly expanded prospecting and mining activity throughout the world has resulted in the discovery of an abnormally large number of new minerals.