What is GRODAN stone wool?

Stone wool products are made from basalt rocks, which come from the Earth. Stone wool is composed roughly of the following elements:

46% Silica, 16% Calcium, 14% Aluminum, 1% Magnesium, 8% Iron, 2% Sodium, 1% Titanium, 1% Potassium, and 1% Manganese (Source: Cultivos vegetales en substratos C.T.I.F.L.)

In the production process, a biologically derived binder is used and some lime stone which can leave some lime residue on the surface of the fibers.

Mimicking Mother Nature's production of "angel hair" during volcanic activity, the GRODAN stone wool manufacturer heats rocks to 1600°C, to create lava. The lava is blown into a spinning chamber, which makes fibers similar to cotton candy. These fibers are bagged loosely as "stone wool granulate". They are also packed into mats, from which GRODAN cubes, blocks and slabs are cut. The products make excellent use of natural resources: one cubic yard of rock becomes 37 cubic yards of wool!