Manganese Dioxide
Formula: MnO2
| DENS - Density (Specific Gravity) |
4.9-5.0 |
Above 1080C, half of the oxygen disassociates to produce MnO, a flux that immediately reacts with silica to produce violet colors in the absence of alumina, browns in its presence. Thus if it is being used in glazes fired below 1080C it should be considered as MnO2, if above it should be taken as 81.5 MnO and 18.5 LOI.
In glazes it will behave in a refractory manner, stiffening the melt. Because to the expulsion of oxygen at 1080, glazes using manganese should avoid this temperature range to reduce the chance of blistering and ruining of the glaze surface.
This material is available as a pure material or as a ground ore (pyrolusite). Thus while generically it is pure MnO2 the actual name-brand materials may only be 75% MnO2.
Manganese dioxide is the key to Rockingham brown wares which are made by employing about 3% iron oxide and 7% manganese in a transparent lead glaze of a recipe such as: Feldspar 28, Kaolin 14, Flint 4, Lead bisilicate 40, Whiting 4.
Manganese browns have a different, often more pleasant character than iron browns.
Manganese oxides can occur in a number of less common forms: (i.e. Mn2O3, Mn3O4, Mn2O7).
Mechanisms
Body Color - Black When added to terra cotta bodies in amounts around 5% manganese dioxide will produce dark gray to black firing bodies. Glaze Color - Metallic Large amounts of manganese can produce metallic effects in a glaze. However, these glazes must not be used on food surfaces.
Out Bound Links
- (Hazards - General)
Manganese Inorganic Compounds Toxicology
Manganese can be very toxic, expecially with regar... - (Materials - Unspecified)
Manganese Granular - MnO2 - Manganese, Granular Pyrolusite
Granular Manganese
- (Materials - Unspecified)
Manganese Oxide - MnO - Pyrolusite, Manganese (black)
MnO, Manganese(II) Oxide
- (Hazards)
Manganese in Clay Bodies
Hazards of these materials in ceramic glazes and c... - (Temperatures)
Manganese dioxide decomposes to MnO (535C-?)
- (Minerals - Parent mineral)
Hübnerite
A manganese mineral. - (Typecodes)
1: GNM - Generic Material
- (Typecodes)
1: CLT - Colorant
- (MDT - Member)
New Zealand
We are working on this database and would apprecia... - (MDT - Member)
Latin and South America
Latin America and South America. We are working on... - (MDT - Member)
Europe
Countries of Eastern Europe and former Soviet Unio... - (MDT - Member)
Australia
We are working on this database and would apprecia... - (MDT - Member)
Asia
All of Asia including Turkey, Russia, Indosnesia, ... - (Minerals - Parent mineral)
Manganite
Ore of manganese. - (MDT - Member)
Africa
All of continental Africa. We are working on this ... - (MDT - Member)
North America
The decision about what materials to include in th... - (MDT - Member)
Ron Roy
This is the traditional Ron Roy materials file. He... - (MDT - Member)
UK
We are working on this database and would apprecia... - (MDT - Member)
Crystal Glazes
These materials are specially defined for makers o... - (MDT - Member)
Enamel Industry
We are working on this database and would apprecia... - (MDT - Member)
Glass Industry
The materials included in this MDT were selected i...
In Bound Links
Pictures
G2571A cone 10R dolomite glaze with 5% manganese dioxide
Cone 10R dolomite matte glaze with 5% manganese dioxide
An example of variegation on a tile surface that occurred when using raw manganese dioxide (likely due to gassing)
Metallic oxides with 50% Ferro frit 3134 in crucibles at cone 6ox. Chrome and rutile have not melted, copper and cobalt are extremely active melters. Cobalt and copper have crystallized during cooling, manganese has formed an iridescent glass.
XML for Import into INSIGHT
<?xml version="1.0" encoding="UTF-8"?>
<material name="Manganese Dioxide" descrip="" searchkey="Mno2, Pyrolusite, Manganese(IV) oxide" loi="0.00" casnumber="301678-04-6">
<oxides>
<oxide symbol="MnO2" name="Manganese Dioxide" status="" percent="100.000" tolerance=""/>
</oxides>
</material> | 
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