Barea and Emery are typical mesosiderites, whereas Dyarrl Island is unique in having the lowest metal content and the highest FeO/(FeO + MgO) ratio of any meteorite of this class. Average pyroxene compositions have been determined for the individual mesosiderites, and show a sequential increase in FeSiO3 content, ranging from a mean of 21 mole % for Veramin to 45 mole % for Dyarrl Island. Steinbach may possibly be classed as a mesosiderite, since its mineralogy is identical except for the absence of plagioclase. Dalgaranga and Mt. Padbury may be a paired fall. The chemical and mineralogical composition of the silicate material of the mesosiderites is similar to, but not identical with the howardites; the overall range of composition is greater in the mesosiderites.

A series of albites was synthesized in the presence of aqueous NaOH fluids (concentration 0 to 4N NaOH, Pfluid = 15000 1b/in2) over the temperature range 300 to 500 °C. At fixed temperature-pressure conditions increasing NaOH concentration of the initial fluid can be correlated with decreasing obliquity of the albites.

Lattice parameters have been determined for two coexisting siderite phases in concretions of Westphalian age. Chemical evidence indicates that, for one concretion at least, the phase of smaller cell dimensions is a magnesian siderite with around 25 mole % MgCO3. Both abundances and compositions of the two phases vary between concretions whilst a single phase only is present in disseminated siderite. It is thought unlikely that the two phases represent an equilibrium assemblage and a mechanism is suggested by which magnesian siderite could have formed later.

The potash feldspar in the charnockites is orthoclase and they are inferred to have been formed around 700 °C. A twin-law study of the plagioclase indicates an igneous origin of the charnockites and pyroxene granulites. The KD values of the coexisting pyroxenes in the granulites are appropriate to equilibrium at 670 °C. A substantial substitution of A1 for Si in the values of the coexisting pyroxenes in the granulites are appropriate to equilibrium at 670 °C. A substantial substitution of A1 for Si in the Z group in all mafic minerals studied also indicates relatively high temperatures of formation. Almandine is pyroperich, a result of high pressure. The charnockites and pyroxene granulites are inferred to be formed under conditions of high pressure and temperature.

Approximately forty, variously shaped, chromitite bodies occur in dunites and harzburgites of the alpine-type peridotite complex of southern New Caledonia. The chromitites consist of pichrochromite (59 to 42% Cr2O3) and serpentinized olivine (Fo96-92) and display a variety of textures (massive, disseminated, and orbicular) consistent with a magmatic cumulate origin. Dunites contain olivine (Fo93−97) and 1 to 3% picrochromite (50 to 39% Cr2O3). Harzburgites have less than 1% spinel, ranging from picrochromite to ceylonite (45 to 28% Cr2O3) and often forming symplectic intergrowths with bronzite. Temperatures of crystallization of the cumulate picrochromites are believed to have been about 1200 °C while the more aluminous symplectic spinels equilibrated under different conditions and may reflect a late stage recrystallization episode.

Nahcolite (NaHCO3) is identified and recorded for the first time from an igneous rock. Often associated with it is another carbonate mineral tentatively identified as kalicine (KHCO3), which has not previously been recorded as a primary mineral in any rock. These minerals occur in inclusions in apatite crystals in ijolites and carbonatites, and indicate that both ijolite and carbonatite magma must have been considerably richer in soda and potash than is indicated by the chemical analyses of the rocks. The identification was made by a combination of microchemical, solubility, crystallographic, and optical determinations.

Heyite occurs in silicified limestone with other oxidation-zone minerals derived from galena, chalcopyrite, and pyrite. The occurrence is near Ely, Nevada. Most common are pyromorphite, cerussite, and chrysocolla. Heyite occurs on and replaces corroded tungstenian wulfenite. Crystals are small (up to 0·4 mm), simple in habit, and monoclinic. Only {001}, {100}, {110}, and {01} have been observed. Twinning on {110} is relatively common. The colour is yellow-orange with a yellow streak, H = 4. Electron probe analyses (average of three) gave PbO 75·4 %, ZnO 0·81 %, FeO 8·41 %, V2O5 12·65 %. This leads to Pb5(Fe,Zn)2(VO4)2O4, with Z = 1.

The space group is P21/m. Cell constants, refined from powder data, are a 8·910 Å, b 6·017, c 7·734 (all ±0·004 Å); β III° 53′±4′. The strongest powder lines (Cr-Kα) are: 3·248, 11, (100); 2·970, 30, 21 (69); 2·767, 211 (61); 4·873,110, (46); 3·674, 111, (35); 2·306 (33); 3·010, 020, (29); 3·412, 20, 11, (25); 8·281, 100, (25); and 2·113 (20). Gcalc 6·284, Gmeas 6·3±0·2 Optically biaxial with 2Vγ 82°calc, 89°meas; αD 2·185, βD 2·219, γD 2·266; all values ±0·01 and determined in S-Se melts. Dispersion is weak with π > ν. The orientation is β = b, α: [001] 36° (in obtuse β). Nonpleochroic.

Three small specimens were found, and represent a total of less than 100 mg of the mineral. One has been deposited with the British Museum (Natural History). The name is for Dr. Max Hey, eminent British chemist and mineralogist.

The cell is strikingly similar to that of brackebuschite but electron probe examination of a newly analysed (by atomic absorption) specimen of the latter from the type locality in Argentina shows a marked chemical difference. Heyite strongly resembles descloizite in appearance.

The Pre-Cambrian granitic rocks of Bygland are structurally and texturally concordant with the metamorphosed country rocks. Both these rock types plot close together in Q-Or-Ab and Ab-An-Or normative diagrams; trace element distribution is also similar. The granite has been reconstituted from the country rocks under epidote-amphibolite facies conditions. Plagioclase feldspars show that the granite is not a ‘mature’ rock; they are, however, ‘mature’ in the country rocks and are products of typical regional metamorphism (Ohta et al, 1968). Plagioclases in the granite are relicts of country rocks showing traces of a premetamorphic crystalline state. They have been rejuvenated with the introduction of alkali material during the reconstitution.

Chemical analyses, cell parameters, and optical data are presented for conjugate cummingtonite and hornblende, which occur in a paragneiss. A metasomatic origin for the development of hornblende from cummingtonite, during retrogressive metamorphism, is proposed.

The electron spin resonance spectrum of a sample of natural, orange-coloured fluorite from Broken Hill, Australia, has been observed and shown to arise from the presence of manganese ions. From an analysis of the structure of this spectrum it has been possible to estimate the various contributions to the ionic energy level splitting and to show that these are in good agreement with comparable results for synthetic material. It is evident that the manganese ions have entered the lattice substitutionally at Ca2+ sites and the nature of this site is discussed.

Biphosphammite, ammonian KH2PO4, syngenite, aphthitalite, monetite, hannayite, whitloekite, apatite and minor gypsum, taylorite, brushite, mirabilite, guanine, and unidentified compounds form crystalline crusts on the walls and floors of a chamber of Murra-el-elevyn Cave, Cocklebiddy, Nullarbor Plain, Western Australia. The minerals are derived from the interaction of bat urine, droppings, and limestone. Analyses for CaO, MgO, Na2O, K2O, SO3, P2O5, CO2, NH3, H2O-, total N, and ignition loss are given. High K2O and low total N figures are characteristic of the analyses.

Tantal-aeschynite occurs as idiomorphic metamict crystals in the Raposa pegmatite at São José do Sabugí, Paraíba State, NE. Brazil. Morphological data, microscopic properties, and differential thermal analysis results are given. Electron-microprobe analyses yielded a formula: {Ca0·28(Yt,Ln)0·425(Th,U)0·11}(Ta0·75Ti0·62Nb0·595Fe0·05)O6. Yttrium is the predominant rare-earth element, with cerium and neodymium as most abundant lanthanides. The tantal-aeschynite unit cell has (after heating) a 5·34, b 10·97, c 7·38 Å. An indexed X-ray powder pattern (similar to that of aeschynite) is presented.

Investigation of the mineralogy and paragenesis of the fluorspar flat at Masson Hill, Matlock, Derbyshire, shows the mineralization to be a combination of void infilling and metasomatic replacement. The main paragenesis is of the non-sulphides, fluorite, baryte, and calcite accompanied by a sequence of sulphides, bravoite, pyrite, marcasite, chalcopyrite, sphalerite, and galena. A wide range of secondary minerals occur in the oxidation zone.

At least four stones fell over a distance of about 9 km at the end of a west to east trajectory on 25 April 1971 at about 1630 hours local time. Their approximate location is 11° 51′ N., 8° 13′ E. About 13·4 kg of this xenolithic bronzite chondrite, class H4, were recovered. A bulk chemical analysis with total Fe = 29°4 % (wt), is presented. Olivine is Fa18.9 (molec.) in composition. Concentrations of the cosmogenic radionuclides 22Na, 26Al, and 54Mn were 71±6, 56±5 and 84±6 dpm/kg, respectively.

Heyite (see preceding paper) is so strikingly similar to brackebuschite that a close comparison of the two species seemed advisable. Topotype brackebuschite (B.M. 55819) was used for this purpose.

Brackebuschite is a vanadate of lead, manganese, and iron, heyite a vanadate of lead and iron. Both species are monoclinic with diffraction symmetry P21 or P21/m. The X-ray cells are remarkably close: a = 8·810, 8·910; b = 6·155, 6·017; c = 7·651, 7·734; β = 111° 30′, 111° 53′ (brackebuschite first). As might be expected, powder patterns are strikingly close as well.

Other than the similarities noted above, the minerals differ so fundamentally that they cannot be the same—they are valid and distinct species. Optic orientations show α: [001] 20° (in acute β) for brackebuschite, 36° (in obtuse β) for heyite. Indices are (brackebuschite first): α 2·28, 2·185; β 2·38, 2·219; γ 2·49, 2·266 for the sodium D line.

Chemical differences are irreconcilable and reaffirm brackebuschite as Pb2(Mn,Fe,Zn)(VO4)2.H2O while heyite is Pb5Fe2(VO4)2O4.

Further lines of the anomalous optical absorption spectrum in low metamict zircon have been observed in the infra-red. Low-temperature polarization studies have enabled a clear distinction to be made between lines due to the anomalous spectrum and those due to the normal spectrum of U4+ in zircon. Magnetic circular dichroism measurements showed, for the anomalous spectrum, only contributions due to the mixing of the energy levels by the magnetic field; thus the A spectrum results from singlet → singlet transitions. The anomalous spectrum appears to derive from U4+ incorporated in polycrystalline zirconia.

In the Dahomeyan of the western Accra Plains mafie gneisses, amphibolites, and ortho-amphibolite dykes in granitic gneiss occur. During the latest recrystallization, metamorphic conditions ranged (north to south) from oligoclase-epidote amphibolite subfacies through andesine-epidote amphibolite subfacies to at least the medium or upper part of the amphibolite facies. Chemical analyses of hornblende, garnet, and clinopyroxene from two mafic gneiss specimens supplement data from the Mampong specimen (Knorring and Kennedy, 1958) and indicate that mineral compositions are largely controlled by rock compositions.