Causes of hexagonal basalts
The composition of this rock is small and dense, the main components of olivine, pyroxene. On the ground can often see the basalt of the basalt, which is the basaltic cooling volume shrinkage caused by a crack. This crack is often hexagonal, square,
On land, it can cover more than one European country - France, and 70% of the surface area of the ocean at the bottom of almost all basalt composition.
Basalt is a common spouting rock. Basaltic magma viscosity is small, fluidity, easy to overflow a large number of surface, the formation of a large area of basalt cover.
