Omphacite (Jd46.1–52.0Ae0–8.4Aug48.0–51.2) and diopside (Jd4.3–6.3Ae0–0.4Aug93.6–95.6) coexist in a vein cutting an omphacitite block in a serpentinite melange of the Oeyama ophiolite, central Chugoku Mountains. The compositional gap between omphacite and diopside is significantly wider than for other omphacitediopside pairs reported in the literature. The intergrowth texture of the omphacite-diopside vein suggests that the clinopyroxene pair was contemporaneously crystallized in the fracture from a Ca-bearing, alkali-rich fluid in a sub-solvus condition. Such a fluid may have been introduced from the surrounding serpentinized clinopyroxene-bearing harzburgite. The stability of omphacite and Al-rich pumpellyite in the matrix and the omphacite-diopside vein indicate that the earlier matrix recrystallization and later fracture filling may have both taken place under high-P-T condition during the melange-forming stage.

Sixteen fluorapatite specimens from regional skarns in granulite terrain were associated with Al-zoned diopside ± scapolite ± actinolite ± calcite(+ rare phlogopite). Apatite was low in Ce (ave. 0.19% Ce2O3) and enriched in LREE relative to HREE (La/Yb = 31 to 74 in 4 specimens). Some specimens showed small negative Eu anomalies and some crystals were zoned in REE. SrO averaged 0.36%. The mineral contained some carbonate (ave. 0.5% CO2 in 5 specimens), appreciable silica (ave. 0.5%), and variable sulphate (0.1 to 1.2% SO3). Excess charge due to S6+ was largely compensated by Si4+. Chlorine was minor and F accounted for 75–98% of the F, Cl and OH ions. Apatite from marble lacking amphiboles and pyroxenes has a similar chemical composition, but apatite from later carbonatite and fenite contains more Ce and Sr. Apatite from Gatineau fenite, Gatineau carbonatite and world-wide siliceous igneous rock generally contains less S. Apatite from Gatineau skarns normally contains more Cl and less S than that from phosphorite. Magnesian marble was silicated to skarn by reaction with siliceous gneiss. Phosphorus, REE, and Sr were removed from nearby rocks and transported in aqueous, carbonated solutions containing minor amounts of F, Cl and S at granulite-facies conditions. Apatite and calcite precipitation took place in skarns and marble during the Grenville (Proterozoic) orogeny.

Short-range order in the oxygen co-ordination shell of the Ca ion in a glass of composition Ca3Mg4Al2Si7O24 is investigated by analysis of the extended X-ray absorption fine structure. The estimate of disorder in the short-range oxygen co-ordination is no greater than that for crystalline samples of diopside and bytownite. An estimate of the oxygen environment of calcium in the particular glass is included.

Alluvial rubies and sapphires are found in palaeodrainage deposits along the Cudgegong-Macquarie River system, central eastern New South Wales, Australia. A pink to red suite contains Cr (up to 0.6 wt.% Cr2O3) as the main chromophore, exceeding Fe (up to 0.5 wt.%Fe2O3). Corrosive etching suggests a prior xenocrystic Mesozoic-Cenozoic basaltic transport, while Cr2O3/Ga2O3 to Fe2O3/TiO2 ratios indicate an original metamorphic source. Syngenetic mineral inclusions include Al-rich diopside, meionite and anatase. The Al-rich diopside (‘fassaite’) contains extremely high Al2O3 (20–21 wt.%). A blue-green suite contains Fe (up to 0.8 wt.% Fe2O3) as a dominant chromophore, while a rare nepheline-anorthoclase composite inclusion supports a magmatic phonolitic origin. The Cudgegong- Macquarie ruby formation is compared with a garnet granulite origin proposed for Thailand rubies and a xenolith of corundum-bearing garnet granulite from Ruby Hill, Bingara, Australia. Clinopyroxenecorundum thermometry suggests the Cudgegong-Macquarie rubies formed at T >1000–1300ºC, a high equilibration T for proposed lithospheric granulites. These rubies form a distinctive suite compared to other rubies from Australian and SE Asian basalt fields, but have some similarities with eastern Thailand rubies.

Pyroxene and mica found in plutonic rocks of the Little Murun ultrapotassic pluton exhibit trends of compositional evolution that permit evaluation of the differentiation sequence of the complex. Pyroxene evolves from diopside in kalsilite and phlogopite pyroxenites through aegirine-diopside in shonkinite to aegirine in late stage charoitite and evolved hypabyssal rocks. The compositional trend is unusual in that the hedenbergite content of the pyroxenes never exceeds 15 mol.% and is thus unlike pyroxene compositional trends found in sodic alkaline complexes. Mica is Al- and Ti-poor and ranges in composition from Fe-rich phlogopite through biotite towards tetraferriannite. Compositional trends of mica found in ‘lamproite-like’ hypabyssal rocks are identical to those observed in the micaceous plutonic rocks; hence the former are considered to be representatives of the lamprophyric facies of the magmas which formed the plutonic series.

A series of matrix operations is described which enables the following optical data to be calculated for plane polarized light perpendicularly incident on a section of a transparent or opaque mineral: 1. vibration directions and refractive indices of anisotropic transparent minerals: 2. reflectivities and the state of polarization of light reflected from anisotropic opaque minerals. The data needed are the dielectric tensor, its orientation with respect to the crystal axes, the unit cell parameters and the direction of the incident light. The mathematical techniques involve the manipulation of matrices, the determination of eigenvalues and eigenvectors and, for opaque minerals, the manipulation of complex numbers. All operations can be carried out with the aid of some of the recent electronic calculators which have built-in matrix algebra procedures and complex arithmetic.

Computer simulation techniques have been used to investigate defect formation and the diffusion of Ca and Mg in diopside. It was found that isolated, non-interacting CaO and MgO Schottky defects had the lowest formation energies (3.66 and 3.97 eV respectively); oxygen Frenkel defects are the most favourable oxygen defects (formation energies 3.93 eV). Magnesium and calcium self-diffusion in the c-direction of diopside is easiest by a vacancy mechanism involving either direct jumps along the c-direction, or double jumps in the b-c plane. In the extrinsic regime, diffusion activation energies for Mg are predicted to be 9.82 eV (direct route) and 1.97 eV (double jump route); for Ca diffusion, activation energies are predicted to be 6.62 eV (direct route) and 5.63 eV (double jump route). If additional vacancies (oxygen or magnesium) are present in the vicinity of the diffusion path, Ca migration energies fall to 1.97–2.59 eV. At elevated temperatures in the intrinsic regime, diffusion activation energies of ⩾ 5.95 eV are predicted for Mg self-diffusion and 9.29–10.28 eV for Ca self-diffusion. The values for Ca diffusion are comparable with published experimental data. It is inferred that a divacancy mechanism may operate in diopside crystals.

Far-from-equilibrium dissolution experiments with diopside and basaltic glass in mixed-flow reactors at 70°C and pH 8.2 show that solute concentrations do not reach steady state over the experimental duration of 45—60 days. Chemical modelling indicates that during the dissolution experiments, solutions have become supersaturated with respect to carbonates in the case of diopside, and carbonates, clay minerals and zeolites in the case of the basaltic glass. Decreasing dissolution is therefore interpreted as a result of secondary surface precipitates blocking the reactive surface area. Calcite formation was supported in both experiments by a significant increase in Ca (and Sr) concentrations as pH was abruptly lowered from 8.2 to 7 because this change increased carbonate solubility and caused all potential carbonate precipitates to re-dissolve. The reduction in pH also led to an increase in Si concentration for diopside and a decrease in Si concentration for basaltic glass. This observation is in accordance with previous experiments on the pH-dependent dissolution rates of pyroxenes and basaltic glass.

Wollastonite (CaSiO3)–diopside (CaMgSi2O6) glass-ceramic scaffolds have been successfully fabricated using two different additive manufacturing techniques: powder-based 3D printing (3DP) and digital light processing (DLP), coupled with the sinter-crystallization of glass powders with two different compositions. The adopted manufacturing process depended on the balance between viscous flow sintering and crystallization of the glass particles, in turn influenced by the powder size and the sensitivity of CaO–MgO–SiO2 glasses to surface nucleation. 3DP used coarser glass powders and was more appropriate for low temperature firing (800–900 °C), leading to samples with limited crystallization. On the contrary, DLP used finer glass powders, leading to highly crystallized glass-ceramic samples. Despite the differences in manufacturing technology and crystallization, all samples featured very good strength-to-density ratios, which benefit their use for bone tissue engineering applications. The bioactivity of 3D-printed glass-ceramics after immersion in simulated body fluid and the similarities, in terms of ionic releases and hydroxyapatite formation with already validated bioactive glass-ceramics, were preliminarily assessed.

Studies were carried out in 1983 to determine the relative abundance and species composition of three lepidopterous stem borers in upland and irrigated rice at Ibadan, southwestern Nigeria. The relationship between irrigated rice crop phenology and the population of the borers and stalk-eyed fly was also studied.

White stem borer, Maliarpha separatella was the predominant species in upland and irrigated rice, followed in upland rice by pink stem borer, Sesamia calamistis, and striped stem borer, Chilo zacconius and in irrigated rice by C. zacconius and S. calamistis. The proportion of M. separatella was higher in irrigated rice than upland. Three population peaks were observed annually in both upland and irrigated rice.

Studies on the relationship between irrigated rice phenology and field population of lepidopterous borers and a dipteran borer showed that the stalk-eyed fly, Diopsis spp., occurred before 20 days after transplanting (DAT) in ITA 212 and continued up to 90 DAT: the peak was observed at 40 DAT. The lepidopterous borers did not appear until 40 DAT and populations peaked at 80 DAT.