What is the end or edge of a vein nearest the surface. [U.S.] Apex of the earth's motion (Astron.), that point of the heavens toward which the earth is moving in its orbit called?

apex — (Mining) The end or edge of a vein nearest the surface. [U.S.] Apex of the earth's motion (Astron.), that point of the heavens toward which the earth is moving in its orbit. (Webster's 1913.)