The question of defining on a common basis the products which are made
available to user industries has long been a cumbersome issue. The members of
EUROFEL have agreed on a standardised definition of the feldspar products which
are placed on the EU market.
According to that harmonised definition, feldspar products are aluminosilicates with Si02 content >58%,
Alkali content (Na20+K20) > 2%, Alumina content
(Al203) > 3% and loss on ignition < 3%.
Three distinguished families exist:
Feldspatic sand:
with an alkali content (Na20+K20) < 6% or alumina
content (Al203) < 8%
Pegmatite:
with an alkali content (Na20+K20) >6% and alumina
content (Al203) comprised between 8 and 14%
Feldspar:
with an alkali content (Na20+K20) >6% and alumina
(Al203) content > 14%.
A further distinction can be made between Sodium, Potassium and mixed
feldspars, depending on the type of alkali they contain.
The producers which are members of EUROFEL have endorsed this harmonised
definition and have decided to apply it to all their feldspar products. In
relation to this, they have also implemented an interlaboratory comparison
system which allows, for each of the criteria included in the definition, to
compare the specifications provided by the producers on a reliable basis. The
results of these interlaboratory tests are available from each of the
participating companies and on the present site.
