The analysis of an acid-soluble and acid-insoluble fraction of one systematically sampled, partially dolomitized limestone bed is reported. The original lime sediment, composed principally of skeletal remains, pellets, occasional intraclasts, detrital quartz, illite, and muscovite has been modified by the addition of calcite, dolomite, and dickite cements and has been patchily replaced by dolomite, quartz, and pyrite. Rapid chemical and mineralogical variations occur over short distances, i.e. within 10 m. Fe and Mn are both present in greater concentration in dolomite than in calcite. Dolomite itself varies in overall composition within the limestones and dolostones but is always Sr-deficient. The insoluble residue is dominated by quartz. Authigenic quartz occurs but its distribution is controlled by pre-existing detrital quartz so SiO2 distribution corresponds to a detrital arrangement. TiO2 and K2O follow the distribution of SiO2 and are believed to be sited in detrital minerals, muscovite, and other unidentified minerals. Sulphur, present in pyrite, has a patchy distribution but is deficient in totally dolomitized areas suggesting removal of pyrite during dolomitization.

Almost 400 specimens of natural and synthetic quartz were γ-irradiated and then heated. Polarized absorption spectroscopy, EPR, and spectrochemical analysis were used to investigate the various colors produced.

A blue color originated from absorption by the A1 and A2 bands at 1·85 and 2·55 eV. The substitutional A1 EPR hole-type center usually considered to be the cause of the color in smoky quartz does not correlate with A1 and A2, but with A3, a previously unreported absorption band at 2·90 eV. The A1 and A2 absorptions bleach at temperatures as low as 280 °C and as high as 360 °C the range for A3 being 140 to 380 °C. The B band at 3·95 eV was previously reported only in irradiated fused silica.

Greenish-yellow colors (appearing yellow when of low intensity) were observed after irradiation (followed by heating in some instances) in many specimens of natural and synthetic quartz; the color originates from the tail of a strong absorption band in the ultraviolet. The bleaching temperature range is the same as that for A2.

The wide variation in color of natural and irradiated smoky quartz can be explained by combinations of the smoky (A3), blue (A1 and A2), and greenish yellow absorption features.

Portions of the carbonatitic fluids responsible for the deposition of apatite from the Tororo car-bonatite complex are trapped and preserved as minute (< 100 µm) inclusions within the apatites. These fluids consist predominantly of alkali-carbonate-bearing brines and demonstrate that water and alkalis played an important role in the formation of the carbonatites from this complex. Furthermore, the opinion that carbonatite ‘magmas’ are richer in alkalis and water than the chemistry of the carbonatites themselves reveal is clearly substantiated. The mean minimum formation temperature of the apatites from five separate carbonatite samples were determined from the homogenization temperatures of 200 primary aqueous inclusions. The results from Limekiln Hill samples (328 °C 321 °C 359 °C) are similar to those from samples of the separate carbonatite mass at Tororo Rock (353 °C, 365 °C).

Ruizite is a new mineral found in the mesogene calc-silicate assemblage at the Christmas mine, Gila County, Arizona. Occurs with kinoite, apophyllite, smectite, and junitoite. Colour is orange inclining to brown with pale streak, H = 5, Sp. Gr. meas. = 2·9. Crystals monoclinic 2/m, elongate on [010]; a = 11·95 Å, b = 6·17, c = 9·03, β = 91° 22½′. Probable space group P21/c with Z = 4 giving Dcalc = 2·997. Strongest lines are 11·951 Å(10), 4·190 (7), 3·116 (6), 5·092 (5), 3·644 (4), 2·951 (4), 2·591 (4), 2·132 (4). Indices are α = 1·663, β = 1·715 ‖ [010], γ = 1·734, 44° to [001] in obtuse β; 2Vα = 60·2°; inclined dispersion p > v strong. Twinned on {100}. Analysis by wet methods gave CaO = 20·57%, Mn2O3 = 23·42, SiO2 = 39·14, H2O = 16·0 leading to or CaMn3+ (SiO3)2(OH). 2H2O.

Named for its discoverer, Joe Ana Ruiz of Mammoth, Arizona

Investigation of serpentine minerals from metaserpentinized ultramafic rocks in two Archaean green-stone belts, east of Kalgoorlie, has indicated that antigorite, exhibiting a very wide range of textures in thin section, is the dominant serpentine species; however, it is locally accompanied by relict lizardite. Chrysotile occurs both in late tectonic veins and as a present-day weathering product of relict olivine. Analytical data and structural formulae on seven serpentines, characterized independently by X-ray diffraction analysis, support the chemical differences between antigorite and chrysotile postulated by earlier workers.

Claringbullite, Cu4CI(OH)7.nH2O where n is about 0·5, a new mineral, is reported as soft blue plates in cuprite from Nchanga open pit, Zambia and Kambowe, Mina M'sesa, Katanga. The mineral is hexagonal a 6-6708, c 9·183 Å, Z = 2. Optically, claringbullite is uniaxial negative with ω = 1·782 and ε = 1·780. Indexed powder data are given together with five electron-probe analyses of the mineral.

The changes in olivine morphology and grain size upwards through comb-layered olivine eucrite and peridotite varieties of harrisite in the Rhum layered pluton are systematic, from abundant small granular crystals, to fewer and larger hopper crystals, to highly elongate branching crystals, which are preferentially elongate along the a axis and perpendicular to the plane of the layering. These changes have been reproduced in the laboratory by cooling water-bearing melts (P = 5 kb) of harrisite at 14 and 30 °/hr. These cooling rates represent maximum values for natural crystallization of comb-layered harrisite. Other experiments suggest that the oriented branching olivines in the rock crystallized at 30–50 °C supercooling. The results indicate that continuous, rather than abrupt, changes in the degree of supercooling and supersaturation of the magma can cause formation of comb layers. They also indicate that while field relations point to growth of most comb layers along a thermal gradient in the magma, this is not an essential condition for comb layer formation. Growth could be along a compositional gradient instead. During crystallization of a comb layer, both nucleation rate and the number of crystals suspended in magma close to the layer are essentially zero. Conditions initiating and terminating comb layer formation and the origin of the rapid vectorial crystallization are discussed. It is suggested that some comb layers could form without change in degree of supercooling, due to rapid removal of crystals suspended in the magma causing the enhanced growth rate and branching style of growth of the remaining crystals. Multiple origins of comb-layered rocks may therefore be possible.

Ten rather uniform tholeiitic basalt flows totalling a thickness of 190 m from Sagar, India, contain two stratigraphical breaks. Major element variation allows the flows to be grouped into two eruption cycles. Due to intraflow variation, however, chemical composition is unlikely to be useful in widespread correlation of flow sequence. The initial 87Sr/86Sr ratios vary from 0·7039 to 0·7084 with Rb and Sr averaging 6·5 and 184 ppm respectively and Rb/Sr ratios ranging from 0·002 to 0·224, with no systematic relationship between the initial 87Sr/86Sr ratios and other chemical parameters. Bulk crustal contamination is considered unlikely; selective introduction of 87Sr from the granitic basement is postulated.

The Mineralogical Society celebrated its 50th Anniversary in 1926; this address attempts to summarize the substantial developments in the subject over the past 50 years and looks ahead to the future. Up to 1926, only the techniques of goniometry, optical investigation of non-opaques, and classical chemical analysis had been fully exploited. X-ray crystallography, though already 14 years old, had made little impact but was to advance with great rapidity to achieve, for example, the modern conception of silicate structure by 1934. The insight into the atomic structure of minerals provided by this technique has been central to the advancement of the subject. The powder camera and more recently the counting diffractometer have become the chief determinative tools, though microscopy is still important. Diffractometry with a tied computer has greatly speeded up structural work. Advances in electron microscopy may soon make it possible to produce direct images of atomic structure. Meanwhile wet-chemical procedures have largely given place to spectroscopy (optical emission, X-ray, and atomic absorption), to the electron microprobe and to various still more advanced techniques, including the investigation of stable and unstable isotopic composition by mass spectrometry. Independently, the optical identification of opaque minerals has been brought to an advanced state. All these developments have opened the way for progress in the understanding of the paragenesis and genesis of minerals, subjects to which experimentation at high temperatures and pressure now contribute materially; and for practical applications in many fields, including ore deposits, beneficiation, ceramics, refractories, cement, sinters, and fuels.

The petrological interpretation of the variation of K2O content with depth to the Benioff zone in orogenic magmas is complicated by several factors: (1) Magmas may not be true primary liquids but have under-gone differentiation. K2O contents, at a specific SiO2 level, will depend upon the SiO2 content of the parental magma and the natureof the crystallizing phases more than on original K2O content. (2) The depth to the Benioff zone may not give a true reflection of the depth of melting. Magmas may not be derived from the uppermost layer of subducted oceanic crust but rather the overlying upper mantle. Earthquakes may not occur in the uppermost layer of the subducted plate, but in its colder, central parts. Hence, earthquake depth may not be related to the source of the magma. (3) It is difficult to envisage how the temporal increase in K2O may occur in certain areas (e.g. Aleutian I., Fiji) if it is primarily controlled by the depth to the Benioff zone.

There may be some correlation between K2O content of magmas and earthquake depth, but its cause is difficult to determine. None of the existing explanations is entirely satisfactory, and it is suggested that varying degrees of fractional crystallization may play an important role in controlling K2O contents.

Zincian högbomite has formed by hydrous alteration of spinel and biotite in a lens of highly aluminomagnesian sapphirine-bearing granulite-facies rocks. The högbomite forms chestnut-brown {0001} flakes 1 mm across. ε = 1·827, ω = 1·852 (− 0·002). Analysis: BeO 0·10, SiO20·65, Al2O3 59·69, TiO2 5·37, Ga2O3 0·23, Nb2O5 0·01, Fe2O3 5·24, SnO2 0·06, NiO 0·04, ZrO2 0·03, MgO 7•69, Sc2O3 0·01, CoO 0·11, ZnO 3·08, FeO 17·52, In2O3 0·05, MnO 0·12. The pattern of d-spacings is anomalous. Other högbomites from the region have exsolved from cordierite or titaniferous opaque oxides.

Luetheite was found at a small prospect in Santa Cruz County, Arizona, as crystals in vugs in rhyolite porphyry. A few specimens were found on the dump, none seen in place. Occurs in silicified porphyry (quartzsericite-alunite) with chenevixite and hematite. Crystals indian blue inclining to greenish, H = 3, Dmeas = 4·28.

Crystals monoclinic 2/m and tabular on a {100}, also a plane of distinct cleavage; other forms are {110}, {140}, {011}. Space group perhaps P21/m with a = 14·743Å, b = 5·093, c = 5·598, β = 101° 49′; strongest lines are 3·498Å (10), 310, 111; 7·208 (7), 200; 2·507 (5), 120, 510. Feebly pleochroic in pale blue in thin section, γ = β > α. Indices are α = 1·752, β = 1·773, γ = 1·796; 2Vγ = 88° (calc.); dispersion is moderate ν > ρ. α ∥ [010], γ: [001] 10° in obtuse β. Duplicate chemical analyses averaged CuO 28·9%, Al2O3 18·4%, As2O5 40·5%, H2O 9·3% giving 2[Cu2Al2 (AsO4)2(OH)4·H2O].

Named for R. D. Luethe, geologist for Phelps Dodge Corporation. Chenevixite from Las Animas, Sonora, analysed to give Cu2Fe2(AsO4)2(OH)4·H2O. Powder data are close to luetheite, and the cell is monoclinic 2/m, probably P21/m, with a = 15·006A, b = 5·189, c = 5·724, β = 102°15. The measured specific gravity is 4·38, Dcale. = 4·59. Crystals tabular on a {100} with a habit very similar to luetheite. Indices are α = 1·92 , β = 1·96, γ = 2·04, 2Vγcale. = 75°; α ∥ [100], γ nearly ∥ [001].

A new calcium aluminum silico-phosphate mineral has been found at two locations on Newry Hill, Newry, Maine, U.S.A. Its composition closely approximates to 3CaO.3·5Al2O3.3SiO2.2P2O5.18H2O (Z = 1). Perhamite is uniaxial (+), c = 1577, ω = 1·564, density = 2·64 g/cm3. The mineral is hexagonal, probably P6/mmm, with a = 7·02 Å, c = 20·21 Å. The colour is light brown to white, the habit is as aggregates of discoidal hexagonal crystals. Cleavage is perfect {0001}, the lustre is vitreous, and the streak white. The mineral is named for a pegmatite miner and geologist, Frank C. Perham of West Paris, Maine, U.S.A.

The most similar species is viséite. A re-examination of viséite indicates that the composition previously given is incorrect. A new form of viséite, also from Visé, Liège, Belgium is also examined and found to differ in composition from the type material.

Kerolites from Goles Mountain (Yugoslavia), Wiry (Poland), Madison Co. (North Carolina), and Kremze (Czechoslovakia) are compared with talc and stevensite. Chemical analyses give a composition for kerolite near R3Si4O10(OH)2.nH2O with R mainly Mg and n about 0·8–1·2. Infra-red data and dehydration-rehydration experiments suggest that the additional water is partly surface-held hydrogen-bonded molecular water, lost up to about 300 °C and easily recoverable, and ‘water’ held as surface hydroxyls, lost at temperatures up to about 650 °C and less easily recoverable. The surface area of kerolite from North Carolina by nitrogen absorption measurements is 196 m2/g.

X-ray data show broad basal reflections, a basal spacing (after Lorentz-polarization correction) of about 9·6 Å and a crystallite size of about five structural layers, which is consistent with the large surface area. Two-dimensional hk bands indicate a randomly stacked layer structure with b ≈ 9·14 Å and a crystallite ‘diameter’ of about 150 Å. The basal spacing shows no expansion in water and no thermal contraction up to 500°C. A partial and irregular swelling with ethylene glycol is obtained only after prolonged cxposure (several weeks). In both respects, kerolites differ from stevensite. Kerolites come close to talc in structure and composition but differ in having a highly random layer arrangement, a slightly enlarged basal spacing, which could be due to misfit of layers caused by random stacking, and weaker interlayer bonding.

Kerolite is considered to be a useful varietal name for this talc-like mineral in agreement with the views of D'yakonov and of Maksimovic. It cannot be defined as serpentine + stevensite.

Isolated pockets of pegmatitic appinite characterized by hollow-shell, prismatic amphiboles are common in the Pre-Cambrian metagabbros and metasomatic diorites of Jersey. Field relationships and petrography indicate a liquid phase in the formation of these appinitic pockets, which are chemically distinct from the associated gabbros and diorites. Close chemical ties between appinites and host rocks, however, prove a replacive, metasomatic, rather than intrusive origin for the pockets. Significant enrichment in SiO2, K2O, and Na2O suggest that surrounding granite provided the metasomatic agents. The localized changes in composition of the basic rocks resulted in the formation of partially molten pockets from which the appinites crystallized. This mechanism probably necessitates a temperature in the region of 900 °C at 2–5 Kb PH2O: Fractured, hollow-shell, prismatic amphiboles of the pockets are consistent with quench crystallization, possibly due to the sudden loss of volatiles. An increase in the oxygen fugacity may have played a major role in inducing the rapid crystallization of kaersutitic amphibole. The envisaged conditions under which these changes took place are those of a high-level, sub-volcanic environment.

Analyses are presented for an iron-rich pentlandite associated with native copper and troilite from New Zealand and three cobalt-bearing pentlandites from Australia. Examination of 141 published analyses indicates that pentlandites, regardless of their Co content, can be classified on the basis of cell size, Fe content, Fe:Ni ratio, and the sulphide assemblage in which they occur. The cobaltian varieties show two separate trends.

Archerite, (K, NH4)H2PO4, a new mineral, has been found in Petrogale Cave, 36 km east of Madura Motel (31° 54′S, 127°00′E) Western Australia. Archerite and biphosphammite together with aphthitalite, halite, syngenite, stercorite, oxammite, weddellite, whitlockite, guanine, newberyite, calcite, (NH4)2Ca(HPO4)2·H2O, and an unknown occur as stalactites and wall and floor crusts.

Archerite is tetragonal with second order prisms and pyramids in crystals up to 2 mm in length with D 2·23, ω 1·513, ε 1·470, all close to artificial KH2PO4. The mineral is soft, has a white streak, and is soluble in cold H2O. Cell dimensions of natural archerite were not determined and the composition was calculated from measurements of selected powder lines correlated with charts prepared from end-member data and by chemistry which gave 81% KH2PO4 and K2O 10·8, NH2 3·46 respectively, the latter corresponding to (K0·74(NH4)0·26)H2PO4.

The name is for Dr. M. Archer, Curator of Mammals, Queensland Museum. Type material is stored in the collections of the Government Chemical Laboratories, Perth, Western Australia.