Composition and phisio-chemical characteristics

Ghassool is an entirely natural mineral product essentially composed of clayish stevensite ore based on silicate of magnesia.

A mineralogical and chemical control take place on a regular basis by experts to ensure the conformity of the Ghassoul, with the norms established by the Moroccan government and published in the official newspaper of Morocco. After the Ghassoul’s underground exploitation it does not contain a single micro-organism or parasite that could create an inconvenience for living beings.

Optical Microscope Aspect

Through optical microscope, Ghassoul that is ready for use appears like a grayed end and on this amorphous and colloidal background you can see thin flakes. Not a single plant debris has been noted.

Electronic Microscope Aspect

Electronic microscope exams show that the crystal network structure of Ghassoul presents important analogies, without it having a perfect identity of facies, with the other minerals of the stevensite family and the magnesian montmorillonites. These clays are constituted of large piled layers that are usually 100x50x2 nm.


The density of brut Ghassool is determined with pycnometers and approximately 1,7

Moisture Content

The moisture content is determined at 180ºC, by weighting to a constant weight. The loss of weight by drying is approximately at 13%

Ash Content

The total ashes are a result of a complete calcination at 600 ºC, in a Caldwell crucible containing the sample already dried at180ºC. The ashes are of approximately 18%

Chemical Analysis

The base cations present are determined on the residue of the fluoroperchloric attack of Ghassoul. The silica content, expressed in silicate (SiO2) represent 55,0% (p/p) of Ghassoul.

Results of Chemical Analysis

In the following table you will find the results of chemical analyses in % of Ghassoul by different researchers:

Damour (1843) Barthoux (1923)   Jeannette (1952)     Faust, Hataway & Millot (1959)
SiO2 55,00 51,42 58,00 57,45 56,30 50,30 55,02
Al2O3 1,20 0,89 1,40 0,85 2,60 12,85 1,12
MgO 28,00 20,75 28,10 26,90 26,50 13,85 24,89
CaO 0,01 2,92 0,85 1,30 0,95 0,75 0,54
Fe2O3 1,40 1,04 0,80 1,00 0,80 3,35
Na2O 0,28 0,60 0,40 0,70 1,05 0,54
K2O 0,52 0,56 0,50 0,60 0,45 3,42 0,43
S 0,15 0,20 0,30 0,40
SO3 0,34
P 0,80 0,17 0,30 0,20 0,45
CO2 3,00 4,80 4,80 4,75 0,30
FeO 0,70
Li2O 0,36
F 3,22
H2O 10,35 20,70 6,10 6,45 6,50 8,10 7,66
X-ray powder diffraction analysis

X-ray powder diffraction analysis of Ghassoul shows similarities between stevensites of different origins and Ghassoul, as the following results show (X-ray powder diffraction of hectorites, Ghassoul and stevensites):

Ore Exchange Capacity of cations in meq/100g
Ghassoul, Morocco 75,1
Hectorite, California 60,8
Stevensite, Patterson New Jersey 37,6
Thermal differential Analysis

The differential thermal curb of analysis realized with a temperature increase of 10 ºC/mm reveals an important endothermic phenomenon between 120 ºC and 160 ºC which corresponds to the beginning of the inter follicular of water in montmorillonites. The minerals of recrystallisation obtained after heating at 1000 ºC and 1200 ºC are:

  • The cristobalite
  • The enstatite

the curb analysis and the minerals of recristallisation are typical of a very magnesian montmorillonite.

Power of ions exchange

The study of the exchanging properties of ions in stevensites, Ghassoul and hectorites show that the 2 latter are close by their high capacity of exchanging cations that would be 75 meq/100g of Ghassoul while it is only 37 meq/100g for stevensite. In the following table are indicated in meq/100g, the distribution of the different exchangeable cations in percentage for Ghassoul (according to Faust):

Exchangeable Cations Meq/100g Oxydes in %
Mg++ 55 MgO 1,13
Na+ 17 Na2O 0,15
K+ 3 K2O 0,53
Ca++ 2 CaO 0,06
Analysis of Ghassoul
  Organoleptic Exams
Aspect   Powder
color   Brown
Physico-Chemical Characteristics
Granulometric   <500 micro m
Loss of drought   < 15%
Total Ashes   <15%
Microbiological Analysis
Total Germs   <10000/g
Yeasts, molds   <1000/g