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Natural iron precipitates in a mine retention pond near Jabiru, Northern Territory, Australia
The objectives of this paper are to: a) report on the detailed characteristics of the red-brown precipitates forming the sludge plumes in retention pond 4; b) describe and characterise the red-brown precipitate coating the organic mat over the pond
floor in areas adjacent to the plumes during times of low water level; c) speculate on the processes of formation of the precipitates, and; d) comment in their environmental significance.

New evidence of an organic contribution to manganese precipitation in iron-formation and review of sedimentary conditions in the Cuyuna North Range, Minnesota
in the precipitation of manganese. The microstructures suggest that microbial precipitation may have been a dominant factor in the precipitation of both iron and manganese in the Trommald Formation.

This paper describes the occurence and distribution of Fe and Mn oxides associated with hydrothermal activity on the mid-ocean ridges and discusses some of the mineralogical and chemical characteristics of the Fe and Mn precipitates. Studies of Fe
and Mn oxides at seafloor hydrothermal vents have focussed primarily on the inorganic precipitation of metals, but routine mineralogical and chemical analyses of these deposits reveal abundant microbial forms and organic carbon which suggest
that microorganisms may participate in the precipitation of Fe and Mn.

The objectives of this paper are to: i) describe the types of gelatinous, red-brown, iron-rich precipitates found in waterlogged surface layers of recently-formed, saline, sulfidic soils and compare these precipitates with those that befoul
boreholes in the same area and ii) elucidate the biogeochemical processes of iron mineral formation in both the gelatinous red-brown iron-rich precipitates formed during the wet season and yellowish iron-rich crusts formed in the dry season.

Mineralogy of precipitates formed by the biogeochemical oxidation of Fe(II) in mine drainage

from microbiological manganese precipitation during the acme of marine transgressions of oxygen-stratified seas, the latter being the result of cyclicity operating on the crustal-hydrosphere-atmosphere system.

This paper reports findings about nodules, Mn microbiology, and soil characteristics and presents some ideas about microbial precipitation of the nodules.

Iron minerals in surface environments

and the precipitation of Fe minerals. Examples illustrate the diverse interactions between the formation of Fe minerals and the biosphere, the results of which are frequently manifested in colorful soils and sediments around the world.

The genesis of supergene products in the sedimentary Mn deposits on Groote Eylandt is the subject of detailed investigations. Among the many geochemical and biological mechanisms which may have influenced the mobilization or precipitation of ores

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