close box The applications which
can use this mineral are
highlighted. Please select
one to learn more.
Product Description
Benefits & Application Details



Magnetite (iron oxide, chemical formula Fe3O4) is a dense, black powder which can be characterised by:

  • High density
  • Ferro-magnetic properties
  • Potential to heat up when subjected to microwave radiation (microwave induced heating).


Basic properties

Property Value Unit
Moisture 0.1 [%]
Hardness (Mohs) 5.5 [-]
Colour black [-]
Density 5.4 [kg/ dm3]


Product overview

Grade + 45 µm D50




Portafer M63 9 10 65

Portafer M is the brand name for Sibelco’s magnetite.



Due to its ferro-magnetic properties, using Portafer M63 it is possible to develop plastic magnetic articles.

Microwave induced heating: microwave radiation enables rapid processes and curing of sealants and adhesives, even of bond lines that are thick or difficult to access. Where metal substrates are used, they will heat up rapidly as well, allowing very fast curing of the sealant or adhesive. When working with non-conductive substrates (ceramics, polymers or composites), adhesives can be modified with appropriate mineral fillers such as magnetite. This will cause direct heating of the bond line and hence rapid curing.


Because of the high thermal stability and the combined high specific heat capacity and density, Portafer M63 also finds use in formulations for friction materials.

Sibelco © 2021