Rubber / Rubber Compounding / Hydromagnesite





Securoc C10 and Securoc D10 products are different blends of two minerals: Huntite and Hydromagnesite

Huntite particles have a platy morphology and the particles are usually about 1 μm or less in diameter, much smaller than hydromagnesite particles. It has the following chemical formula and thermally decomposes between about 450°C and 750°C in two stages, releasing only carbon dioxide, leaving a solid residue of magnesium oxide and calcium oxide:  Mg3Ca(CO3)4 → 3MgO + CaO + 4CO2

The solid residue is called “char” and is critical to obtain smoke suppression . Char coming from Huntite has better mechanical properties than char generated by the thermal decomposition of hydromagnesite (which only consists of MgO – see below).


Property Value Unit
Hardness (Mohs) 1-2 [-]
Refractive index 1.62 [-]
Density 2.7 [kg/ dm3]


Natural hydromagnesite particles have a “blocky” morphology and once processed the majority of the particles are usually between 1 and 10 μm in diameter depending on the processing. 

It thermally decomposes between about 220°C and 550°C in two stages, initially releasing water then carbon dioxide, leaving a solid residue of magnesium oxide:  Mg5(CO3)4(OH)2·4H2O → 5MgO + 4CO2 + 5H2O


Property Value Unit
Hardness (Mohs) 3.5 [-]
Refractive index 1.54 [-]
Density 2.2 [kg/ dm3]


Basic product (mineral blend) properties

Property C10 D10 Unit
Moisture 0.6 0.6 [%]
pH 10 10 [-]
Hardness (Mohs) 2 – 3 2-3 [-]
Refractive index 1.61 – 1.64 1.61-1.64 [-]
Colour (D65/ 10°) L* 98 98 [-]
Ry 93 93 [-]
Density 2.5 2.6 [kg/dm3]


Securoc products overview

Product Grade D50



[g/ 100 g]

Surface treatment
Securoc C10 4 45
C10 F11.0 4 45 1% stearic acid
D10 3.5 50
D10 F12.0 3.5 50 2% stearic acid


Products for rubber compounding:

Product Grade D50


Securoc C/D C10 4
C10 F12.0 4
D10 3.5
D10 F12.0 3.5


Production location: Lefkara (GR), Maastricht (NL)

Application: Securoc C/D products provide flame-retardancy along with good smoke suppression and char-formation, either by itself or in combination with ATH.  

Functionality: Safety

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