In the investigation of a suite of leucite-lamproites from the West Kimberley area of Western Australia, carried out in the Department of Mineralogy and Petrology, Cambridge, during the period 1937–38, a number of unusual minerals were noted. Three of these were isolated and analysed and two of them proved to be new species. The present paper deals mainly with the three minerals analysed. They are—

1. (l) Magnophorite, a new amphibole allied to katophorite.

2. (2) Wadeite, a new potassium-zirconinm silicate.

3. (3) Titaniferous phlogopite.

The leueite-bearing rocks occur at a number of isolated volcanic vents, nineteen of which have been examined and mapped by Dr. A. Wade. They have in every instance broken through sedimentary déposits of Permian age. Considerable diversity is to be seen in the rock types developed, but they are all characterized by high potash, magnesia, and titania, with low alumina and soda. Analyses of some types which indicate the general chemical character of these rocks are given in table I.

Occasion arose recently when the writer required to make a number of comparative areal measurements of irregularly shaped portions of fossil corals in thin section, and it was found that the micrometric methods available were very tedious and involved considerable strain. A micro-planinmter has now been designed by means of which fairly accurate determinations of areas can be made with a minimum of eye strain. Though intended primarily for use with the petrographical microscope with the rotating stage, it can be adapted for use on microscopes of the fixed stage type.

In 1850, T. H. Henry published an imperfect analysis of francolite, a supposed new mineral, previously named by H. J. Brooke. Henry stated that his material was similar to the material from Wheal Franco, Tavistock, Devon, but he does not show how he was in a position to know the composition of the material from this mine, because there is no record to indicate that the mineral from Wheal Franco had been analysed. Henry did not report CO2 for the material he analysed, but M. H. N. Story-Maskelyne and W. Flight analysed material, supposedly similar, and obtained a significant amount of CO2.

The results of a chemical analysis of a mineral are always presented, in the first place, as percentages of elements or oxides present, and until recently the only possible further treatment of these values was to calculate atomic or molecular ratios, group them according to accepted isomorphous groups, and deduce (if possible) an integral chemical formula. The degree of approximation to integral ratios accepted as satisfactory is, of course, quite arbitrary, and a decision as to the degree of complication acceptable in a chemical fornmla has often had to rest on very inadequate evidence. Some workers prefer to adjust the final ratios to show the errors evenly distributed, a procedure which has no real advantages.

In most mineralogical text-books the nepheline-syenite area of Alnö, on the east coast of Sweden, is given as one of the few localities of the rare mineral baddelyite, ZrO2. This information is based on a communication by E. Hussak, who claimed to have discovered the mineral in jacupirangitic varieties of the Alnö nepheline-syenites.

The present writer, being engaged with a petrological and mineralogical revision of the Alnö occurrence, earlier described by A. G. Högbom in his classic memoir of 1895, has in vain looked for the presence of baddelyite. Hussak claimed to have isolated by means of Klein's solution 0·38 gram of pure baddelyite from 100 grams of rock, as well as to have obtained characteristic ZrO2 crystals inn borax bead test. Repeated isolation tests with Clerici's solution on samples from various localities within the Alnö area, however, furnished nothing but residues of melanitic garnet.

Natural nickel-iron alloys have been found in several places on the earth's surface. In addition to alloys containing a low percentage of nickel (about 3%), there are others which contain much higher percentages of nickel (about 70%). To alloys of the latter group the name awaruite is now generally given and it may include josephinite, souesite, and other alloys possessing high nickel content so long as they belong to the same phase and possess identical crystal-structures.

It is of interest to the mineralogist to know whether these alloys conform to the structure of nickel-iron alloys prepared in the laboratory and whether they fit into the accepted phase diagram of the nickel-iron system. It is of interest also to the physicist and the metallurgist to obtain information concerning these natural alloys, because some nickel-iron alloys made in the laboratory are difficult to prepare in a state of true equilibrium. Data derived from the study of the natural alloys may help to throw light upon the structure of these artificial alloys.