MicaFort, Muscovite and Phlogopite Micas, are mineral fillers for a large variety of applications in the polymers and coatings industry.

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Paul Pasquino

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MicaFort is a range of naturally platy minerals manufactured from Phlogopite and Muscovite Mica. You can distinguish the product range by their high thermal stability and high aspect ratio.

MicaFort properties

Unique properties for our MicaFort range products are:

  • chemical inertness
  • hydrophilic nature
  • barrier-forming ability due to parallel particle alignment in matrices
  • high thermal stability (up to 1000°C)
  • elastic but tough particles
  • very low silica content for Phlogopite grades
  • excellent brightness and whiteness for Muscovite grades
  • high dielectric strength and electrical insulation properties.

MicaFort in polymers

An increasing application for MicaFort is in thermoplastic blends. When you compare our MicaFort with other minerals the industry uses to replace fibreglass in polyamide, we can state that MicaFort:

  • reduces warping efficiently
  • the surface finish improves an optimal balance of isotropic mechanical and dimensional properties
  • provides excellent reinforcement on its own or in combination with fibreglass

Compared with other mineral fillers in polypropylene, compounds with MicaFort have a:

  • superior modulus
  • isotropic reduction of the linear thermal expansion coefficient (CLTE)
  • increased heat-rejection temperature
  • possibility to reduce the density

Other polymers that benefit from the unique properties of MicaFort Phlogopite and Muscovite include PE, TPO and PBT. Duroplast polymers such as polyester, polyurethane, epoxy and acrylic all benefit from improved performance and service life. Elastomers are stronger and quickly release from the mould.

MicaFort in coatings

Industrial coatings such as marine, anti-corrosion and chemical resistant paints benefit from the inert nature of MicaFort. As well as the ability to form a barrier to aggressive chemicals. Recent studies have shown that you can achieve the best results with MicaFort MM75 in two-component epoxy coatings. When incorporated into a water-based paint, the laminated MicaFort reduces the cracking of the paint.

With the help of MicaFort you can:

  • improve the lifetime of coatings
  • reduce the water vapour permeability
  • increase the strength of the paint layer

Advantages in roof, wood and tile paint are:

  • improved resistance to cracking
  • stable UV protection during prolonged exposure to the outside air

In cementitious fire-resistant coatings used for the protection of structural steel and concrete, MicaFort contributes to lower flammability while it forms a dense “skin” to prevent the paint from being destroyed during a fire.

Essential benefits of MicaFort for foundry coatings are:

  • better surface finish
  • increased accuracy of the metal casting
  • improved recyclability of the sand cores

Other applications are coatings for the production of rubber tires and heat-resistant paint.

Sustainable Mica sourcing

We want to ensure integrity in your value chain. Hereto we can confirm that LKAB Minerals exclusively source MicaFort from global strategic partners and our exclusive access to high-quality material from Finland.

Because of our extensive mineral processing knowledge, we produce a broad portfolio of Phlogopite and Muscovite Mica products.

MicaFort standard grades

  • Dry ground: PD900, MD500, MD250, MD150, MD100
  • Micronised: MM75, SCM-3W, SX300, SX400
  • Silane coated: PW80S, PW30S
  • Wet ground: PW80, PW30, R302, R120, R90, P66

MicaFort packaging

Our MicaFort product range is available in paper sacks or big bags. Also, some of our MicaFort grades are available in bulk. We advise you to contact your sales representative to find out if this applies to the grade you like to purchase.

Typical properties of MicaFort are as following:

Physical properties of MicaFort

Specific gravity [g/cm³]
Refractive index
1.58 - 1.6
Hardness (Mohs)
2 - 3
pH (ISO 787-9)
8 - 9

Chemical properties of MicaFort

Phlogopite Mica is a hydrated silicate of potassium and magnesium whereas Muscovite Mica a hydrated silicate of potassium and aluminium is.

MicaFort origin

Muscovite is a constituent of acid igneous rocks like granite, pegmatite or alaskite, some regionally metamorphosed rocks and clastic sedimentary rocks, and is a product of alteration. It is a fact that most commercial deposits are derived from pegmatites which contain 1-2% and rarely up to 10% muscovite. Moreover, Mica is found in many regions of the world in the form of pegmatite rock and mica schist.

Phlogopite is associated with metamorphosed limestone and ultrabasic rocks, particularly hydrothermal veins formed through metasomatism of magnesium-rich rocks as well as ultrabasic and carbonatite ring intrusions associated with ancient shield areas. LKAB Minerals’ Phlogopite Mica is sourced from a major deposit in Finland.

MicaFort toxicology

Phlogopite and Muscovite Mica are non-toxic natural minerals. For further information please download the Safety Data Sheets in the box on the right.

MicaFort statements and compliances

Downloads on request

Frequently Asked Questions - MicaFort Micas - Phologpite and Muscovite

  • What is the colour of your MicaFort Mica?


    LKAB Minerals Mica grades can have colour from very white (muscovite mica) to brownish (phlogopite mica).

  • What is the difference between muscovite mica and phlogopite mica?


    Muscovite Mica is a potassium-aluminium based alumino-silicate while Phlogopite Mica is a potassium-magnesium based alumino-silicate. The aluminium content in muscovite is higher than in phlogopite. Alternatively, the magnesium content in phlogopite is much higher than in muscovite.

  • What’s the difference between dry ground and wet ground mica?


    A wet grinding process will delaminate the particles more effectively,  achieving smoother particles, with a higher aspect ratio than a dry grinding process.

  • Which particle size distributions (PSD) are available for the Micas?


    Phlogopite Mica PSD range from D50=18micron to 650micron.

    Muscovite Mica PSD range from D50=11micron to 200micron.

  • Can MicaFort micas be used for food contact applications?


    Based on the information currently available to LKAB Minerals Ltd, we can advise you that the
    uncoated Phlogopite & Muscovite Mica products are compliant under certain references. Please ask for  the FOOD CONTACT COMPLIANCES STATEMENT via our documentation TAB or directly with your sales manager.

  • How should mica be compounded into a polymer?


    You must use our MicaFort micas like any other platy mineral and try not to break the particles and keep the aspect ratio. You can use it similar to HAR talcs and glass fibres.

  • Has mica a high aspect ratio?


    In general, yes, however it can vary a lot depending on the grade. We have MicaFort grades which have very high aspect ratio. Contact your local sales manager for more details.

  • What properties does mica provide to a coating?


    Overlapping mica platelets provide anti-cracking properties (to avoid cracks created when the coating dries). Also, it gives a barrier/protection effect; this is good against corrosion and avoids weathering.

  • What properties does MicaFort Micas provide to a polymer compound?


    In mineral filled thermoplastics MicaFort provide:

    • superior modulus
    • isotropic reduction of Coefficient of Linear Thermal Expansion
    • increase in Heat Deflection Temperature
    • opportunities for compound density reduction versus other mineral fillers
    • excellent reinforcement alone or in combination with glass fibre

    In glass-filled thermoplastics Micas provide:

    • very efficient Warpage reduction
    • improved Surface finish
    • optimal balance of Isotropic Mechanical & Dimensional properties
    • excellent reinforcement alone or in combination with glass fibre
  • Is mica chemically inert?


    Yes, except to fluorhidric acid and concentrated sulphuric acid.

  • Is mica heat resistant?


    Yes, it melts at >1200ºC.