Alpenstock :: Alpenstock (n.) A long staff, pointed with iron, used in climbing the Alps..
Greenstone :: Greenstone (n.) A name formerly applied rather loosely to certain dark-colored igneous rocks, including diorite, diabase, etc..
Penstock :: Penstock (n.) A close conduit or pipe for conducting water, as, to a water wheel, or for emptying a pond, or for domestic uses..