Dominant Morphology Research Articles

The impact of stage and cell type on the prognosis of pulmonary neuroendocrine tumors

In pulmonary neuroendocrine tumors the realization that the extent of nodal disease is related to cell type has led to a controversy as to which is the dominant prognostic factor, stage or morphology. To clarify this relationship, we studied patients treated at our institution over a 23-year period. This is a historical cohort study of patients with confirmed pulmonary neuroendocrine tumors who underwent lung resection from 1980 through 2003. Survivors were contacted by telephone, and recurrences were confirmed by means of histopathology. Cox proportional hazards regression was used to ascertain the joint influence of several risk factors on survival. The mean age of the cohort was 54 years (standard deviation, 15 years), and 100 (57%) were men. The cell types for the 177 eligible patients were typical carcinoid in 89 (50%), atypical carcinoid in 15 (8%), large cell in 22 (13%), and small cell in 51 (29%). The median time to follow-up was 7 years (first to third quartile, 2-12 years), and overall 5- and 10-year survivals were 86% (79%-90%) and 81% (74%-87%), respectively. The univariable predictors of survival were age (P = .001), nodal stage (P = .01), and cell type (P < .001). In the final multivariable model only age (P = .04) and cell type (P < .001) remained as independent predictors. The hazard of death among patients with large cell or small cell lung cancer was highest in the first year and a half after diagnosis, reducing drastically thereafter. In pulmonary neuroendocrine tumors cell type is the predominant determinant of survival. The survival of patients with each cell type is sufficiently diverse to warrant different management strategies. Conservative resection is feasible for typical carcinoids, but the effects of adjuvant chemotherapy need to be evaluated for the other subgroups.

Clonal Light Chain Restricted Primary Intrapulmonary Nodular Amyloidosis

Primary intrapulmonary nodular amyloidosis is a rare form of immunoglobulin associated amyloidosis, also falling under the alternative appellation of amyloidoma. Although amyloidomas in other organ sites may be reflective of a localized or more generalized plasma cell dyscrasia, in the context of its presentation in the lung the presumptive basis has long been held to be one of chronic inflammation. We encountered 2 patients with nodular amyloidosis in whom the pathologic examination disclosed the basis to be one of a light chain restricted clonal lymphocytic plasma cell infiltrate, although without morphologic features of coexisting pulmonary lymphoma. These 2 patients serve to underscore the potential categorization of some cases of pulmonary nodular amyloidosis as a form of low grade B cell lymphoproliferative disease.

Eolian controlled modification of the martian south polar layered deposits

Data from the Mars Orbiter Laser Altimeter (MOLA) and Mars Orbiter Camera (MOC) aboard the Mars Global Surveyor (MGS) mission and the Thermal Emission Imaging System (THEMIS) aboard the Mars Odyssey mission have revealed unique surface features in a particular region of the South Polar Layered Deposits (SPLD). The dominant morphology is large-scale quasi-parallel grooves that extend for hundreds of kilometers with only tens of meters of vertical relief, that we have termed here the “Wire Brush” terrain. The grooves are also transected by disjointed, yet roughly continuous, low-relief sinuous ridges that cross roughly perpendicular to the trend-direction of the large-scale grooves and show only tens of meters of relief. We interpret these ridges to be eroded remnants of folded layers. At the northern end of the large-scale grooves there are non-symmetric mounds. They are frequently preceded by a significant depression and/or trailing grooves that are parallel to the Wire Brush trend. We find that a two-stage process involving winds that intermittently remove a low-density crust exposing the underlying ice to ablation is the interpretation that best explains the multitude of features observed here. These features appear to be currently inactive indicating higher winds in previous epochs.

One step convenient synthesis of crystalline β-Si3N4

Well-crystallized β-Si3N4 was directly prepared at an initial reaction temperature of 150 °C through the reaction of SiCl4 and NaN3 in the presence of a small amount of CCl4. Characterization by X-ray diffraction, high-resolution electron microscopy, X-ray photoelectron spectroscopy and energy dispersive X-ray spectroscopy indicates that the product synthesized is crystalline β-Si3N4. The yield of β-Si3N4 is about 86% based on the amount of precursor SiCl4 used at the initial reaction temperature of 150 °C, and is more than 90% at the reaction temperature of 200 °C with the product β-Si3N4 in high crystallinity. The dominant morphology of the product is short rods with the growth axis along the [001] direction. The formation mechanism of crystalline β-Si3N4 was discussed briefly, and the role of CCl4 in the formation process of β-Si3N4 was analyzed.

Crystallization and phase separation kinetics in blends of linear low-density polyethylene copolymers

We have systematically studied the crystallization and liquid–liquid phase separation (LLPS) kinetics in statistical copolymer blends of poly(ethylene- co-hexene) (PEH) and poly(ethylene- co-butene) (PEB) using primarily optical microscopy. The PEH/PEB blends exhibit upper critical solution temperature (UCST) in the melt and crystallization temperature below the UCST. The time evolution of the characteristic morphology for both crystallization and LLPS is recorded for blends at various compositions and following a quench from initial homogenous melts at high temperature to various lower temperatures. The crystallization kinetics is measured as the linear growth rate of the super structural crystals, whereas the LLPS kinetics is measured as the linear growth rate of the characteristic length of the late-stage spinodal decomposition. The composition dependence crystallization kinetics, G, shows very different characteristics at low and high isothermal crystallization temperature. Below 116 °C, G decreases with increasing PEB content in the blend, implying primarily the composition effect on materials transport; whereas at above 116 °C, G shows a minimum at about the critical composition for LLPS, implying the influence of the LLPS. On the other hand, LLPS kinetics at 130 °C is relatively invariant at different compositions in the two-phase regime. The length scale at which domains are kinetically pinned, however, depends strongly on the composition. In a blend near critical composition, a kinetics crossover is shown to separate the crystallization dominant and phase separation dominant morphology as isothermal temperature increases.

Highly symptomatic adult polycystic liver disease: options and results of surgical management.

The majority of patients afflicted with adult polycystic liver disease (APLD) are asymptomatic. For those who are symptomatic, there are a variety of treatment procedures that have been proposed but these lack verification through long-term studies with respect to safety and long-term effectiveness. Choice of surgical procedure is related to the severity of APLD and morphology of the cysts within the liver. The aim of the present study was to analyse the immediate and long-term results of fenestration and combined resection-fenestration at Singapore General Hospital. A retrospective analysis of clinical, operative, imaging and follow-up data was carried out for 12 patients (10 women and two men) with symptomatic APLD who underwent surgery from January 1992 to December 2000. The primary outcome measures assessed were postoperative alleviation of symptoms, performance status, complications, mortality and long-term recurrence of symptoms. Nine patients underwent 12 fenestration procedures and three patients had combined resection-fenestration. Fenestration was carried out for eight of nine patients with a dominant cyst morphology and combination resection-fenestration was carried out for those three patients with diffuse cyst morphology. There was no operative mortality and all patients were discharged from hospital free of their preoperative symptoms. Overall morbidity rate was 58%. The mean follow up for the present cohort was 29.3 months. Only two patients had recurrence of symptoms. One patient with dominant cyst morphology who underwent laparoscopic fenestration had recurrence at 26 and 43 months but this was successfully treated finally with open fenestration. The other patient had diffuse cyst morphology and was treated with fenestration for recurrent cyst infection that recurred 1 month postoperatively. This required subsequent intravenous antibiotics and percutaneous drainage for resolution of symptoms. Treatment for symptomatic APLD should be based on the morphology of the liver cysts. Fenestration is a safe and acceptable procedure for patients with a dominant cyst pattern where liver size can be reduced after the cysts collapse. A combination of resection-fenestration is suitable for those with a diffuse cyst pattern where grossly affected segments are resected in combination with fenestration to allow for reduction in liver size.

Development of EVOH-kaolinite nanocomposites

This paper reports on a novel route to develop EVOH-kaolinite nanocomposites by a melt intercalation process and on some relevant nanocomposite properties as a function of composition. The kaolinite clay used is a very cheap raw material of the tile industry and as such needed to be refined and chemically modified prior to the melt intercalation step. The modification was carried out with dimethyl-sulfoxide, methanol and octadecylamine in order to increase the basal plane distance of the original clay by a factor of more than three. Melt blended nanocomposites were characterized by WAXS, TEM, DSC, TGA and oxygen transmission rate. From the early results, partial exfoliation and intercalation of the clay platelets was the dominant morphology attained. An increase in thermal resistance, glass transition temperature, crystallinity and barrier properties to oxygen were also observed for mass clay loadings below 8%.

Characteristics of Sites and Morphology of the stomach cancer incidents in Jejudo, 2000

Objectives: The aim of this study is to describe the distribution of sites and morphologic findings of the stomach cancer in Jejudo.Methods: From the Jejudo Regional Cancer Registry databases, the subjects were constructed by condition of the incidents of stomach cancer in 2000 among Jejudo residents. The databases also supplied the individual information of the topology and morphology on subjects.Results: The order of ranks in the topology and morphology of stomach cancer was nearly same as that of Korea Central Cancer Registry databases, which represented the nationwide condition of cancer incidence. However, there were some differences in dominant site and morphology between men and women.Conclusions: The results showed that the occurring mechanism of stomach cancer would not be different between Jejudo and other area of Korea. But some further studies to evaluate sex-related risk factors of stomach cancer should be necessary near future.

Morphology of core-shell-corona aqueous micelles: II. Addition of core-forming homopolymer

The poly(styrene)- block -poly(2-vinylpyridine)- block -poly(ethylene oxide) triblock copolymer PS 200 - b -P2VP 140 - b -PEO 590 , where the subscripts refer to the number average degrees of polymerization, forms spherical micelles in water, that consist of a PS core, a pH-responsive P2VP shell and a PEO corona. This triblock has been added with homo-PS before micellization in order to increase the volume fraction of the core-forming block. The length of the added homo-PS has been varied with respect to the length of the PS core-forming block: much shorter, much longer and approximately the same. The structure of the micelles has been investigated by transmission electron microscopy, static and dynamic light scattering. Homo-PS phase separates whenever its length is larger than the one of the PS core-forming chains; otherwise this phenomenon occurs beyond a critical concentration that depends on molecular weight. The addition of homo-PS has no influence on the morphology of the micelles and on the characteristic size of both the PS core and the P2VP shell, although the hydrodynamic diameter of the micelles is decreased. Substitution of styrene for homopolystyrene results in transition from a spherical to a dominant rod-like morphology.

Morphology of core-shell-corona aqueous micelles: II. Addition of core-forming homopolymer

The poly(styrene)- block-poly(2-vinylpyridine)- block-poly(ethylene oxide) triblock copolymer PS 200- b-P2VP 140- b-PEO 590, where the subscripts refer to the number average degrees of polymerization, forms spherical micelles in water, that consist of a PS core, a pH-responsive P2VP shell and a PEO corona. This triblock has been added with homo-PS before micellization in order to increase the volume fraction of the core-forming block. The length of the added homo-PS has been varied with respect to the length of the PS core-forming block: much shorter, much longer and approximately the same. The structure of the micelles has been investigated by transmission electron microscopy, static and dynamic light scattering. Homo-PS phase separates whenever its length is larger than the one of the PS core-forming chains; otherwise this phenomenon occurs beyond a critical concentration that depends on molecular weight. The addition of homo-PS has no influence on the morphology of the micelles and on the characteristic size of both the PS core and the P2VP shell, although the hydrodynamic diameter of the micelles is decreased. Substitution of styrene for homopolystyrene results in transition from a spherical to a dominant rod-like morphology.

Investigation of primary fine particulate matter from coal combustion by computer-controlled scanning electron microscopy

The particle size distributions, morphologies, and chemical composition distributions of 14 coal fly ash (CFA) samples produced by the combustion of four western U.S. coals (two subbituminous, one lignite, and one bituminous) and three eastern U.S. coals (all bituminous) have been examined by computer-controlled scanning electron microscopy (CCSEM). The samples were obtained from a 50-kW combustor using an isokinetic sampler and separated aerodynamically using a cyclone into PM fractions that were nominally <2.5 μm in mean diameter (PM 2.5) and >2.5 μm in mean diameter (PM 2.5+). However, the CCSEM particle size distribution results show that particles with mean diameter <2.5 μm typically constitute more than 80% of the total number of particles and particles with mean diameter >2.5 μm account for over 80% of the total particle volume for both the PM 2.5 and the PM 2.5+ fractions. The samples contained from 0.5 to 11.0 wt.% of unburned carbon and carbonaceous PM was the dominant form of PM <1 μm in mean size. Typically, over 80% of carbon-rich PM was <1 μm and over 95% was <2.5 μm in mean size. The dominant carbonaceous PM morphology consisted of roughly spherical carbon particulates ∼10–50 nm in diameter bonded together in complex chains and clusters that were usually <1 μm in size. Glassy phases with rounded and frequently spherical morphologies were the dominant species observed for the inorganic PM. Particle compositions for several hundred inorganic particles are presented as ternary diagrams, which appear to be useful for source attribution. The inorganic PM derived from combustion of western low-rank coals, which are rich in carboxyl-bound Ca, is dominated by Ca–Si–Al glass phases, while that from eastern bituminous coals, which are rich in pyrite, is dominated by Fe–Si–Al glass phases. Important secondary signature glass phases that are also revealed by the ternary diagrams are Na–Si–Al for western CFA and K–Si–Al for eastern CFA.

Synthetic Macroporous Silicas with Multilamellar Structure

We report a novel mixed-surfactant-based synthesis for growing new macroporous forms of silica. The dominant morphology is a fairly regular honeycomb-like construction with roughly 0.5−3-μm pores and 100−200-nm silica dividing walls. These walls consist of mesoscopic multilamellar structures. Interference optical microscopy observation and 23Na and 13C magic-angle spinning NMR diagnosed the single- and double-tailed surfactants with opposite charges on their headgroups, producing equilibrium vesicles spontaneously. A model that accounts for the architecture of the multilamellar silicas with macroporous morphologies involves the deposition of silica in the interfacial regions of contiguous assemblies of silicate−surfactant vesicles. Synthesizing shapes over μ-length scales provides new opportunities for understanding nature's biosilicification processes and potential uses where macroscopic form determines function, such as the separation, sensing, release, and catalysis of macro- and biomolecules.

A basidiomycete isolated from the skeleton of Pocillopora damicornis (Scleractinia) selectively stimulates short-term survival of coral skeletogenic cells

Endolithic fungi bore through the extracellular calcium carbonate skeleton of reef-building scleractinian corals, both healthy and dead, and effect net erosion of coral reefs. Potential fungal interactions with coral tissue were investigated using an in vitro approach suggested by earlier observations of skeletal repair cones at the site of fungal perforation in Porites sp. A fungal strain was isolated from the skeleton of a long-term culture of healthy, tissue-covered, Pocillopora damicornis Linnaeus colonies maintained in a recirculating system in Monaco. As coral soft tissue spontaneously dissociated in vitro, the skeleton became exposed and hyaline hyphae emerged radially from 15% of the total clipped branches. In this study, which was performed between January 2001 and March 2003, 35 skeleton–hypha explants were embedded in agar-based solid medium, yielding 60% hyphal growth. A fungal strain (F19-3-1) of the dominant (80%) morphology was isolated and propagated in agar-based solid medium. The strain was identified by 18S and 26S rDNA gene sequence analysis as a basidiomycete in the genus Cryptococcus. Co-cultures were used to provide experimental exposure of coral soft tissue to the fungus. The fungus extended the survival of coral cells by 2 days, selectively maintaining skeletogenic cell types. This effect may be interpreted as stimulation by the fungus of a short-term coral defense response.

Morphology of mock SDSS catalogues

We measure the geometry, topology and morphology of superclusters in mock Sloan Digital Sky Survey (SDSS) catalogues prepared and reported by Cole et al. (1998). The mock catalogues refer to rCDM and ACDM flat cosmological models and are populated by galaxies so that these act as biased tracers of mass, conforming with the observed two-point correlation function (TPCF) measured using the APM catalogue on scales between 1 and 10 h -1 Mpc. We compute the Minkowski functionals (hereafter, MFs) for the cosmic density fields using SURFGEN and use the available 10 realizations of rCDM to study the effect of cosmic variance in estimation of MFs and shapefinders; the statistics derived from MFs, and used to study the sizes and shapes of the superclusters. The MFs and shapefinders are found to be extremely well constrained statistics, useful in assessing the effect of higher-order correlation functions on the clustering of the galaxy distribution. We show that though all the mock catalogues of galaxies have the same TPCF and similar clustering amplitude, the global MFs due to rCDM show systematically lower amplitude compared to those due to ACDM. This is an indirect, but detectable effect due to non-zero, higher-order correlation functions, and enables us to distinguish successfully the two models of structure formation. Next we establish that scale-dependent biasing leads to different clustering properties for galaxies as against the dark matter background. Thus, we stress the importance of incorporating a realistic treatment of bias in preparing and analysing the mock catalogues before confronting our models with the observed Universe. We measure the characteristic thickness (T), breadth (B) and length (L) of the superclusters using the 10 rCDM realizations. While T ≤ B and T, B ∈ [1, 17] h -1 Mpc, we find the top 10 superclusters to be as long as 90 h -1 Mpc, with the longest superclusters identified at percolation to be rare objects with their length as large as 150 h -1 Mpc. The longest structures of rCDM are found to be almost twice as long as those in ACDM. The dominant morphology of the large superclusters at percolation threshold is found to be filamentary.

Size-Selective Synthesis of Cubooctahedral Palladium Particles Mediated by Metallomicelles

The reduction of [PdCl4]2- by hydrazine in the postmicellar region of even-numbered alkyltrimethylammonium bromides CnTABr (with n = 8 to 16) yielded fairly monodisperse Pd particles with mean diameters in the range 1.6−6.8 nm. Transmission electron microscopy (TEM) measurements indicated that the particle size decreases with increasing length of the alkyl chain, decreasing precursor concentration, and decreasing surfactant concentration. Kinetic measurements demonstrated that the nucleation is a fast process and well separated from the growth. TEM and high-resolution TEM micrographs of the particles suggested that the dominant morphology is cubooctahedral. Composition analysis (1H NMR, total organic carbon, and inductively coupled plasma atomic emission spectroscopy), titration microcalorimetry, and spectroscopic methods (IR, Raman, and UV−vis) revealed that [PdCl4]2- is not the real precursor species in the reduction process. In the presence of a large excess of Br-, [PdCl4]2- transforms to [PdBr4]2-. The ligand-exchange reaction is accompanied by the formation of stoichiometric complex−surfactant aggregates [CnTA]2[PdBr4], and followed by a slow, higher-order aggregation to microcrystals. The organic salt precipitates below the critical micelle concentration but undergoes solubilization above it, leading to the formation of palladate−surfactant metallomicelles. In the postmicellar region, the close proximity of the surfactant molecules to the reduction centers ensures rapid adsorption of the amphiphiles on the surface of the nascent particles, and a protective bilayer is formed, ultimately leading to long-term stability of the Pd hydrosols.

The relation between particle path length distributions and channel morphology in gravel-bed streams: a synthesis

The path length (downstream displacement over a given time period) of individual bed particles in gravel-bed rivers is central to morphological methods for measuring bed load transport rate and is also fundamental to understanding the bed load transport process and the development of channel morphology. Previous studies of particle movement using tracers report predominantly strongly positively skewed frequency distributions of path length with modes close to the point of entrainment. However, gravel-bed rivers often have regularly spaced erosion (scour pools) and deposition (channel bars) sites that are several channel widths apart and it is reasonable to expect that particle path length would reflect this morphological scale, at least during flows large enough to create and modify the morphology. Here, we synthesize and re-analyze results from published bed load tracing experiments in gravel-bed rivers to identify the variety of possible path length distributions for differing channel morphology, channel dimensions, bed particle size, and particle mobility (i.e. flow magnitude) and to look for occurrences of path length coinciding with the length scale of the morphology. The results show that path length distributions may be positively skewed, symmetrical, and uni-, bi-, or multi-modal and may include modes that coincide with known or expected pool–bar spacing. Primary path length modes equivalent to possible pool–bar spacing are more probable at higher non-dimensional bed shear stress, from which it is inferred that both particle mobility and channel morphology exert an influence on particle path lengths and that particle movement is unlikely to be stochastic except at relatively low particle mobility. Existing data are inadequate for more than a preliminary analysis of this problem consequently there is a need for new data collected explicitly and systematically to confirm these preliminary results, isolate the effect of the several variables that influence the characteristics of path length frequency distributions and identify the conditions under which path length coincides with the length scale of the dominant morphology.

Orientation studies of Si-phthalocyanine sulfonic acids cast on SiO x substrates

Layers of dihydroxy silicon phthalocyanine tetrasulfonic acid and oligo-μ-oxo silicon phthalocyanine tetrasulfonic acid were prepared by solution-casting methods. The purity of the material was checked by X-ray photoemission spectroscopy. The orientation of the molecules in respect to the substrate plane was investigated by angle-dependent near-edge X-ray absorption fine-structure spectroscopy. The morphology was characterized by atomic force microscopy. Most samples exhibited a significant orientation that was accompanied by crystalline structures; others had no orientation at all with a dominant amorphous morphology. This behavior indicates that several preparation parameters affect the crystallinity and the orientation of the phthalocyanines.

The spectrum of cutaneous lesions in rheumatoid arthritis: a clinical and pathological study of 43 patients.

Rheumatoid arthritis (RA) is an idiopathic arthropathy syndrome that has a propensity to affect the small joints of the hands and feet with extra-articular manifestations comprising skin lesions, neuropathy, pericarditis, pleuritis, interstitial pulmonary fibrosis and a systemic polyarteritis nodosa (PAN)-like vasculitic syndrome. The most widely recognized skin lesion is the rheumatoid nodule. Other skin manifestations are poorly defined. Using a natural language search of the authors' outpatient dermatopathology databases, skin biopsies from 43 patients with RA were selected for retrospective analysis in an attempt to define the dermatopathological spectrum of RA and its clinical correlates. The biopsies were categorized by the dominant histologic pattern, recognizing that in most cases there were additional minor reaction patterns. Palisading and/or diffuse interstitial granulomatous inflammation was the dominant pattern seen in 21 patients; the lesions included nodules, plaques and papules with a predilection to involve skin over joints. Besides interstitial histiocytic infiltrates and variable collagen necrobiosis, these cases also showed interstitial neutrophilia, vasculitis and pauci-inflammatory vascular thrombosis. The dominant morphology in 11 other patients was vasculopathic in nature: pauci-inflammatory vascular thrombosis, glomeruloid neovascularization, a neutrophilic vasculitis of pustular, folliculocentric, leukocytoclastic or benign cutaneous PAN types, granulomatous vasculitis, and lymphocytic vasculitis and finally occlusive intravascular histiocytic foci for which the designation of "RA-associated intravascular histiocytopathy" is proposed. Rheumatoid factor (RF) positivity and active arthritis were common in this group, with anti-Ro and anticardiolipin antibodies being co-factors contributing to vascular injury in some cases. Immunofluorescent testing in three patients revealed dominant vascular IgA deposition. In nine patients, the main pattern was one of neutrophilic dermal and/or subcuticular infiltrates manifested clinically as urticarial plaques, pyoderma gangrenosum and panniculitis. The cutaneous manifestations of RA are varied and encompass a number of entities, some of which define the dominant clinical features, such as the rheumatoid papule or subcutaneous cords, while others allude to the histopathology, i.e. rheumatoid neutrophilic dermatosis. We propose a more simplified classification scheme using the adjectival modifiers of "rheumatoid-associated" and then further categorizing the lesion according to the dominant reaction pattern. Three principal reaction patterns are recognized, namely extravascular palisading granulomatous inflammation, interstitial and/or subcuticular neutrophilia and active vasculopathy encompassing lymphocyte-dominant, neutrophil-rich and granulomatous vasculitis. In most cases, an overlap of the three reaction patterns is seen. Co-factors for the vascular injury that we believe are integral to the skin lesions of RA include RF, anti-endothelial antibodies of IgA class, anti-Ro and anticardiolipin antibodies.

Effect of the growth parameters on the Ni–Ni 3Si eutectic microstructure

Microstructure of the Ni–Ni 3Si eutectic system from the nickel rich portion of the nickel–silicon phase diagram was studied as a function of the growth conditions and parameters. In the as-solidified condition the microstructure presents a high degree of regularity and uniformity, with an orientation clearly dependent on the heat flux direction. Directional solidification processing in the range of the growth rates from 6.5 to 20 mm/h resulted in a highly regular polycrystalline structure. The dominant morphology was well aligned and lamellar, without any eutectic cells or dendrites. Also, it was observed that its growth mode is highly dependent on the growth rate, since the increase in the growth rate resulted in a decrease in the interphase spacing and microstructure refinement. During hardness testing material exhibited lower hardness than pure Ni 3Si, suggesting improvement in ductility.

LONDONITE, A NEW MINERAL SPECIES: THE Cs-DOMINANT ANALOGUE OF RHODIZITE FROM THE ANTANDROKOMBY GRANITIC PEGMATITE, MADAGASCAR

Londonite, (Cs,K,Rb) Al 4 Be 4 (B,Be) 12 O 28 , is the Cs-dominant analogue of rhodizite. It occurs with rhodizite at Antandrokomby, a dike of granitic pegmatite in the Manandona valley, Antsirabe region, and at Ampanivana and Antsongombato, in the Betafo region south of Mahaiza, all in Madagascar. Londonite occurs in the inner zones and in miarolitic cavities of highly evolved pegmatites rich in red tourmaline. Associated minerals include microcline, quartz, albite, tourmaline (elbaite – liddicoatite – schorl series), Cs-rich beryl, spodumene, danburite, Mn-rich fluorapatite, hambergite, microlite, manganocolumbite, manganotantalite, behierite, and hafnian zircon, among others. Londonite occurs as equidimensional crystals a few millimeters across, and exceptionally up to 7 cm. The dominant morphology is dodecahedral {110} and rare deltoid dodecahedral {221}, modified by tristetrahedral {211}, tetrahedral {111} and very rare cube {100} faces. Crystals are colorless to white to yellow, with a white streak. The luster is vitreous. Crystals are translucent to transparent. Optically, the mineral is isotropic, with an index of refraction of 1.693. Mohs hardness is 8. It has no cleavage or parting, and is brittle with a conchoidal fracture. Its density is 3.34 g/cm 3 (meas.) and 3.42 g/cm 3 (calc.). Londonite is isometric with space group P 43 m. The cell parameters are: a 7.321 (1) A, V 392.30 A 3 , and Z = 1. The three strongest X-ray powder-diffraction lines measured for londonite [ d in A( I )( hkl )] are 2.9898(100)(211), 2.1132(70)(222), and 2.4410(50)(300,221). Electron-microprobe analyses reveal a wide range of K and Cs contents and an overall low abundance of Rb. The empirical formula based on 28 atoms of oxygen and calculated from an average of five analyses from Antandrokomby is: (Cs 0.48 K 0.38 Rb 0.09 Na 0.03 Ca 0.02 Mn 0.01 ) ∑1.01 (Al 3.98 Li 0.02 Fe 0.01 ) ∑4.01 Be 4 [(B 10.99 Si 0.01 ) ∑11.00 Be 1 ] ∑12.00 O 28 , with the proportion of B and Be fixed by stoichiometry. The mineral is named after David London, Professor of Geology and Geophysics, University of Oklahoma, in recognition of his experimental studies of evolved granitic melts and his contributions to our understanding of the origin of granitic pegmatites.