main vein

It seems that he contrived to find the main vein which we lost in the Esperanza mine.

A stringer of ore branching off from the main vein is known as a chute, shoot, or chimney.

When a stringer junctions with a main vein and causes a swelling, a shaft should be sunk at the junction.

There is no other tree that has not a main vein, or a rib, which prolongs the leaf stem straight to the tip.

The branches unite into larger and larger vessels and finally flow into one main vein, the vena cava.