The best way to fully understand the advantages of eclogite, it is crucial to compare it with another typical rock used in the North Sea.

The stone weight needed for a given rock density may be corrected according to the formula:

W=Wo       (Pso/Pw - 1) x Ps

                     (Ps /Pw - 1)  x Pso


W     =  Weight of actual rock

Wo   =  Weight of reference rock

Pw    =  Sea water density ~ 1.025 kg/dm

Ps     =  Actual rock density

Pso   =  Reference rock density = 2.68 kg/dm


 and the stone weight is given by


  W = Wo x k

The factor k below is shown as a function of the rock density.


















To illustrate this formula, we compare 50 kg eclogite (of 3,2 t/m3) with 100 kg granite (of 2,65 t/m3).


W     =   Wo x k


W     =   Weight of Eclogite (density 3,20 kg/dm )

Wo   =   Weight of Granite (density 2,68 kg/dm )

k       =   Factor 0,50 (see graph)



W = 100 x 0,50 = 50 kg.




A 100 kg Granite rock has the same submerged weight/dm2 as a 50 kg Eclogite rock.

A 100 kg Granite rock can be replaced with an Eclogite rock of 50 kg.