Quick stack building block

Claim 1

A generally rectangularly shaped building block comprising: a pair of vertical, opposite, side walls; a pair of vertical, opposite, end walls traverse of said side walls; a pair of opposite upper and lower longitudinally extending faces formed by the top and bottom surfaces of said side and end walls; a generally rectangular wall structure extending centrally across said block between said side walls, and said central wall structure being spaced from said end walls and extending above said upper face of the block and having therein a generally rectangular cavity extending vertically completely through said wall structure; and each end wall including extensions of said side walls for a distance conforming to one-half the longitudinal thickness of said rectangular wall structure, whereby, with multiple courses of laid block, and with a half block stagger of blocks, as between courses, blocks of one course and blocks between courses are interlocked by an upwardly extending portion of said wall structure into indentations between blocks of an upper course of said blocks, and there exists three full cavities: said cavity formed by said wall structure, and two cavities between it and said side walls and said end walls, wherein after blocks are laid, mortar can be introduced into said three cavities in the construction of a block wall.