Manganese oxide minerals have been used for thousands of years—by the ancients for pigments and to clarify glass, and today as ores of Mn metal, catalysts, and battery material. More than 30 Mn oxide minerals occur in a wide variety of geological settings. They are major components of Mn nodules that pave huge areas of the ocean floor and bottoms of many fresh-water lakes. Mn oxide minerals are ubiquitous in soils and sediments and participate in a variety of chemical reactions that affect groundwater and bulk soil composition. Their typical occurrence as fine-grained mixtures makes it difficult to study their atomic structures and crystal chemistries. In recent years, however, investigations using transmission electron microscopy and powder x-ray and neutron diffraction methods have provided important new insights into the structures and properties of these materials. The crystal structures for todorokite and birnessite, two of the more common Mn oxide minerals in terrestrial deposits and ocean nodules, were determined by using powder x-ray diffraction data and the Rietveld refinement method. Because of the large tunnels in todorokite and related structures there is considerable interest in the use of these materials and synthetic analogues as catalysts and cation exchange agents. Birnessite-group minerals have layer structures and readily undergo oxidation reduction and cation-exchange reactions and play a major role in controlling groundwater chemistry.

https://www.pnas.org/content/pnas/96/7/3447.full.pdf

Manganese oxide minerals: Crystal structures and economic and environmental significance

▪ Abstract Manganese(IV) oxides produced through microbial activity, i.e., biogenic Mn oxides or Mn biooxides, are believed to be the most abundant and highly reactive Mn oxide phases in the environment. They mediate redox reactions with organic and inorganic compounds and sequester a variety of metals. The major pathway for bacterial Mn(II) oxidation is enzymatic, and although bacteria that oxidize Mn(II) are phylogenetically diverse, they require a multicopper oxidase-like enzyme to oxidize Mn(II). The oxidation of Mn(II) to Mn(IV) occurs via a soluble or enzyme-complexed Mn(III) intermediate. The primary Mn(IV) biooxide formed is a phyllomanganate most similar to δ-MnO2 or acid birnessite. Metal sequestration by the Mn biooxides occurs predominantly at vacant layer octahedral sites.

Biogenic manganese oxides: Properties and mechanisms of formation

Status review of mercury control options for coal-fired power plants

Mossbauer spectra measured by the Opportunity rover revealed four mineralogical components in Meridiani Planum at Eagle crater: jarosite- and hematite-rich outcrop, hematite-rich soil, olivine-bearing basaltic soil, and a pyroxene-bearing basaltic rock (Bounce rock). Spherules, interpreted to be concretions, are hematite-rich and dispersed throughout the outcrop. Hematitic soils both within and outside Eagle crater are dominated by spherules and their fragments. Olivine-bearing basaltic soil is present throughout the region. Bounce rock is probably an impact erratic. Because jarosite is a hydroxide sulfate mineral, its presence at Meridiani Planum is mineralogical evidence for aqueous processes on Mars, probably under acid-sulfate conditions.

https://science.sciencemag.org/content/sci/306/5702/1740.full.pdf

Jarosite and hematite at Meridiani Planum from Opportunity's Mössbauer spectrometer

The co-existing microphenocrysts of magnetite and ilmenite together with the ferromagnesian silicates in salic volcanic rocks have been analysed with the electron microprobe. The temperatures and oxygen fugacities of the oxide equilibration have been estimated from the curves of Buddington and Lindsley (1965). The co-existing ferromagnesian silicate phenocrysts are either iron-rich olivine, or orthopyroxene or biotite and amphibole; for each of these groups of phenocrysts, the oxide equilibration data are specific and fall on three distinct curves, parallel to experimental oxygen buffer curves. Many of the investigated rhyolites were quenched at temperatures near 900°C, which may represent liquidus temperatures for those with sparse phenocrysts, and also the intrusion temperature of water-undersaturated granites. The composition of the biotite phenocrysts, which are Al-poor and Ti-rich, taken in conjunction with the oxide data, suggest that two Lassen dacites precipitated biotite at a water fugacity of approximately 400 bars. The composition of the later crystallizing ferromagnesian silicates, particularly the pyroxenes which show a wide range in Fe/Mg ratio, is strongly influenced by the prior crystallization of the oxide phases. If the biotite phenocrysts are typical of acid liquids, then they are incapable of generating by fractionation a peraluminous residual liquid; rather they would tend to make a liquid peralkaline.

The iron-titanium oxides of salic volcanic rocks and their associated ferromagnesian silicates

Crystal chemistry of todorokite structure-types. Three types of atomic substitution occur in the tunnel structures: first, substitution of Mn (super 2+) by other divalent cations (e.g., Mg 2 , Ni (super 2+) , Cu (super 2+) , Zn (super 2+) ) in the "walls" formed by chains of edge-shared [MnO 6 ] octahedra, characteristically three octahedra wide; second, replacement of Mn (super 4+) by similar sized cations (e.g., low-spin Co (super 3+) in the "ceilings" or "floors" typically three, but as many as seven or more, [MnO 6 ] octahedra wide; and third, in the tunnel interiors adjacent to Mn (super 4+) vacancies in the "ceilings." Recommendation that the name todorokite be universally adopted for the predominant manganese oxide mineral accommodating divalent cations of nickel and copper in marine manganiferous concretions.--Modified journal abstract.

/pdf/a-review-of-the-todorokite-buserite-problem-implications-to-4lyxm32aia.pdf

A review of the todorokite-buserite problem; implications to the mineralogy of marine manganese nodules

Electron-probe determination of inter-element relationships in manganese nodules

Results of absorption spectra measurements on silicate glasses of various compositions indicate that ions of the first transition-metal series are present in tetrahedral and octahedral sites in silicate melts (glasses). The fractionation patterns observed for transition-metal ions between magmas and silicate minerals can be interpreted according to crystal field theory in terms of octahedral "site preference energies" of transition ions in crystal lattices.

https://science.sciencemag.org/content/sci/144/3621/1001.full.pdf

Site of Preference Energy and Selective Uptake of Transition-Metal Ions from a Magma.

Mineral spectroscopy : a tribute to Roger G. Burns

Clinoptilolite is the predominant zeolite in diagenetically altered volcanic rocks at Yucca Mountain, Nevada, having formed by posteruptive reactions of ground water with vitric tuffs in the pyroclastic deposits. Compositional variations of clinoptilolites in the fractured and zeolitized tuffs not presently in contact with ground water and the vulnerability of zeolites to burial diagenesis raise questions about the long-term stability of clinoptilolite. Equilibrium activity diagrams were calculated for clinoptilolite solid solutions in the seven-component system Ca-Na-K-Mg-Fe-Al-Si plus H{sub 2}O, employing available thermodynamic data for related minerals, aqueous species, and water. Stability fields are portrayed graphically, assuming the presence of potassium feldspar, saponite, and hematite, and using ranges of activities for SiO{sub 2} and Al{sup 3+} defined by the saturation limits for several silica polymorphs, gibbsite, kaolinite, and pyrophyllite. The clinoptilolite stability field broadens with increasing atomic substitution of Ca for Na, and K for Ca, reaches a maximum for intermediate activities of dissolved Al, and decreases with increasing temperature. The thermodynamic calculations show that ground water of the sodium-bicarbonate type is approximately in equilibrium at 25C with calcite and several zeolites, including heulandite and calcic clinoptilolite. Mg-rich clinoptilolites are stabilized in ground water depleted in Ca{sup 2+}. The activity diagramsmore » indicate that prolonged diagenetic reactions with ground water depleted in Al, enriched in Na or Ca, and heated by the thermal envelope surrounding buried nuclear waste may eliminate sorptive calcic clinoptilolites in fractured tuffs and underlying basal vitrophyre.« less

Roger G. Burns

Papers

A review of the todorokite-buserite problem; implications to the mineralogy of marine manganese nodules

Electron-probe determination of inter-element relationships in manganese nodules

Site of Preference Energy and Selective Uptake of Transition-Metal Ions from a Magma.

Mineral spectroscopy : a tribute to Roger G. Burns

Activity diagrams for clinoptilolite; susceptibility of this zeolite to further diagenetic reactions