The uses of micaceous haematite (MIO) exploit its chemistry and structure.  A high powered microscope shows that it is formed of flat over-lapping flakes of haematite, hence the term micaceous (like mica).  Its applications use these properties.

 

Finished MIO feels soapy to the touch and flows almost like water.  Although they are easily washed off with water, the particles are almost impossible to get completely off clothing, so a shiny ore miner could (can) always be recognised by the residual glitter under artificial light or sunlight.

 

Attempts in the 19th century to use the bulk ore for the production of iron were not successful, probably because it is too friable to use in a blast furnace.

 

From the 16th century or before micaceous haematite was used as writing sand, 'Devonshire sand' or 'pounce', to help reduce the spread of ink on hand written documents, prior to the invention of blotting paper.  Unlike pounce made from ground up cuttlefish bones or similar, Devonshire sand leaves a tell-tale sparkle in the ink.

It was also used as a substitute for graphite or to extend more expensive graphite in dry lubricants.  It was added to grease, and a brand 'Gartor' was marketed from around 1900 for bicycle and motor drive chains.  Micaceous haematite on its own or mixed with graphite was used as 'black lead' for stoves.

 

Shiny ore has been used in glaze for pottery ('sparkle ware'), tiles and decorative bricks. Examples, including amateur work, can be seen in the museum at the Kelly mine site.  It has been used as a filler in plastics and rubbers and in friction materials, and is specified as part of the coating for some grades of welding rod.

 

From about the second half of the 19th century the most important application of MIO was in corrosion resistant paints, used in marine applications (hence battleship grey), and for protecting bridges, and particularly railway infrastructure like over-bridges, signal gantries, and other iron and steel features exposed to aggressive industrial conditions.  The MIO flakes plate out to help make the paint impervious to water and oxygen from the air, and to the harmful effects of UV radiation on the carrier film.

 

Griffiths Brothers Ltd of Bermondsey (London) and later Wednesfield (near Wolverhampton) were a significant manufacturer of paints and varnishes and developed the use of the MIO additive.  They were major shareholders in the Ferrubron company, which was the operator of Kelly and Great Rock mines from about 1920, and were therefore well placed to supply MIO paint, particularly to the big railway companies.  As the supply of MIO from south Devon started to fail it was imported from Austria to keep sales going.

 

The Griffiths Bros trade name, Ferrodor, passed by mergers and buy-outs through ICI paints to AkzoNobel, who now supply MIO paints under the Dulux Ferreko brand.

 

There are US and Chinese patents covering processes for making synthetic MIO, while it is still mined in a few places around the world.

 

Opening https://kmi.at/en leads to the website of Kärntner Montanindustrie.  The MIO deposit in Austria and the methods of mining and processing are very different to what was seen at Kelly.