Noélbensonite, a new BaMn silicate of the lawsonite structure type, from Woods mine, New South Wales, Australia

Kawachi, Yousuke; Coombs, D. S.; Miura, Hiroyuki

doi:10.1180/minmag.1996.060.399.11

Cited by 14 publications

(18 citation statements)

References 5 publications

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“…Therefore, the replacement by ilvaite or manganilvaite component in such lawsonite is unlikely because they contain ferrous iron in the ideal formula. Mn 3+ -bearing lawsonite group endmembers, hennomartinite and noélbensonite, contain Sr or Ba in the divalent cation sites, and Mn 3+ replaces Al (Armbruster et al, 1993: Kawachi et al, 1996. However, the studied lawsonite is almost devoid of Sr and Ba (Table 1) This is yet to be confirmed.…”

Section: Discussionmentioning

confidence: 49%

Analysis of Mn-bearing lawsonite occurring in meta-siliceous rocks in Hakoishi serpentinite mélange of Kurosegawa Belt, Central Kyushu, Japan

Ibuki

Ohi

Tsuchiyama

et al. 2010

Journal of Mineralogical and Petrological Sciences

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Mn -bearing lawsonite was discovered in meta -siliceous rocks metamorphosed under the lawsonite -blueschist facies formed at less than 350 °C and 0.8 -1.0 GPa in the Hakoishi serpentinite mélange of the Kurosegawa Belt, Central Kyushu, Japan. The lawsonite deposits were accompanied by those of hematite, braunite (Mn 2+Mn 6 3+SiO 12 ), and quartz, indicating that the rock had metamorphosed under high Oxygen fugacity (f O 2 ) (~ -20 < log f O 2 < -5) at the abovementioned P -T conditions. The Oxygen fugacity led to the conversion of all the iron into ferric compounds and some of the manganese into its trivalent form. As a result, the lawsonite was found to contain a significant amount of (Mn 3+ + Fe

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Section: Discussionmentioning

confidence: 49%

Analysis of Mn-bearing lawsonite occurring in meta-siliceous rocks in Hakoishi serpentinite mélange of Kurosegawa Belt, Central Kyushu, Japan

Ibuki

Ohi

Tsuchiyama

et al. 2010

Journal of Mineralogical and Petrological Sciences

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“…In situ ultraviolet laser ablation (UVLA) 40 Ar/ 39 Ar dating of alkali feldspar from drill core SLT-015 was carried out at the geochronology laboratory of the Universität Potsdam, Germany. A disc was drilled out from the polished surface of a sample using a hollow cored 7 mm diameter mini-drill.…”

Section: Methodsmentioning

confidence: 99%

“…Replacement textures of microcline by noélbensonite and sérandite by witherite, As-rich tokyoite and noélbensonite, are suggestive of late deposition of barium in a hydrothermal system. At the Woods mine, Australia, the type locality of noélbensonite, this mineral replaces sérandite amongst other Mn-bearing minerals [40]. Kawachi et al [40] interpret such replacement as a result of the activity of relatively low-temperature Ba-bearing fluids that infiltrated after the metamorphic thermal maximum that produced sérandite.…”

Section: Evidence For Hydrothermal Mineral Formationmentioning

confidence: 99%

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The Role of Hydrothermal Activity in the Formation of Karst-Hosted Manganese Deposits of the Postmasburg Mn Field, Northern Cape Province, South Africa

et al. 2019

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The Postmasburg Manganese Field (PMF), Northern Cape Province, South Africa, once represented one of the largest sources of manganese ore worldwide. Two belts of manganese ore deposits have been distinguished in the PMF, namely the Western Belt of ferruginous manganese ores and the Eastern Belt of siliceous manganese ores. Prevailing models of ore formation in these two belts invoke karstification of manganese-rich dolomites and residual accumulation of manganese wad which later underwent diagenetic and low-grade metamorphic processes. For the most part, the role of hydrothermal processes and metasomatic alteration towards ore formation has not been adequately discussed. Here we report an abundance of common and some rare Al-, Na-, K- and Ba-bearing minerals, particularly aegirine, albite, microcline, banalsite, sérandite-pectolite, paragonite and natrolite in Mn ores of the PMF, indicative of hydrothermal influence. Enrichments in Na, K and/or Ba in the ores are generally on a percentage level for most samples analysed through bulk-rock techniques. The presence of As-rich tokyoite also suggests the presence of As and V in the hydrothermal fluid. The fluid was likely oxidized and alkaline in nature, akin to a mature basinal brine. Various replacement textures, particularly of Na- and K- rich minerals by Ba-bearing phases, suggest sequential deposition of gangue as well as ore-minerals from the hydrothermal fluid, with Ba phases being deposited at a later stage. The stratigraphic variability of the studied ores and their deviation from the strict classification of ferruginous and siliceous ores in the literature, suggests that a re-evaluation of genetic models is warranted. New Ar-Ar ages for K-feldspars suggest a late Neoproterozoic timing for hydrothermal activity. This corroborates previous geochronological evidence for regional hydrothermal activity that affected Mn ores at the PMF but also, possibly, the high-grade Mn ores of the Kalahari Manganese Field to the north. A revised, all-encompassing model for the development of the manganese deposits of the PMF is then proposed, whereby the source of metals is attributed to underlying carbonate rocks beyond the Reivilo Formation of the Campbellrand Subgroup. The main process by which metals are primarily accumulated is attributed to karstification of the dolomitic substrate. The overlying Asbestos Hills Subgroup banded iron formation (BIF) is suggested as a potential source of alkali metals, which also provides a mechanism for leaching of these BIFs to form high-grade residual iron ore deposits.

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“…2). The vein-filling constituents are prismatic jadeite crystals along the vein wall, with Kawachi et aL (1996) …”

Section: Discussionmentioning

confidence: 99%

Itoigawaite, a New Mineral, the Sr Analogue of Lawsonite, in Jadeitite from the Itoigawa-Ohmi District, Central Japan

Matsubara¹

1999

Mineralogical Magazine

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Itoigawaite, SrAI2Si207(OH)2.H20 , is a new member of the lawsonite group found in the ItoigawaOhmi district, central Japan. it is orthorhombic, Cmcm, a = 6.031(2), b = 8.945(2), c = 13.219(4) A, Z = 4. The strongest lines in the X-ray powder diffraction pattern are 4.68 (s) (111) on the basis of O -10. It is transparent, blue in colour with vitreous lustre. The streak is white and the cleavage good in one direction. The hardness is 5-5.5. The calculated density is 3.3 g cm 3. It is colourless in thin section and optically biaxial positive with ~ = 1.664 (2), [3 = 1.674 (2), 7 -1.688 (2) and 2V(calc.) = 81 ~ It occurs in a thin veinlet cutting a lavender-coloured Ti-bearing jadeitite. The veinlet includes irregularly-shaped aggregates composed of minute tabular crystals of itoigawaite up to 50 ~tm across and minute jadeite crystals with interstitial natrolite aggregates. Itoigawaite is considered to be crystallized from fluid during later stage activi~ of high-P/T metamorphism. The name is for the locality.

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Noélbensonite, a new BaMn silicate of the lawsonite structure type, from Woods mine, New South Wales, Australia

Cited by 14 publications

References 5 publications

Analysis of Mn-bearing lawsonite occurring in meta-siliceous rocks in Hakoishi serpentinite mélange of Kurosegawa Belt, Central Kyushu, Japan

Analysis of Mn-bearing lawsonite occurring in meta-siliceous rocks in Hakoishi serpentinite mélange of Kurosegawa Belt, Central Kyushu, Japan

The Role of Hydrothermal Activity in the Formation of Karst-Hosted Manganese Deposits of the Postmasburg Mn Field, Northern Cape Province, South Africa

Itoigawaite, a New Mineral, the Sr Analogue of Lawsonite, in Jadeitite from the Itoigawa-Ohmi District, Central Japan

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