European standards do not apply quantitative Petrography. There is also no European test to identify the phyllosilicates. At European level, the problem of clays is globally handled using the Methylene blue test, which lacks of preciseness in our opinion.

Clays and phyllosilicates in filler aggregates have been the object of standardisation in Switzerland for more than 30 years. Swiss standards required an adaptation to the modern techniques of analyses of minerals and must be compared with the European testing methods