Complex sentence: Mary Laughlin donated a block of land on June 6,1865, as a site for the mint and in 1869, construction finally began with Harvey A. Hogue as the superintendent of construction.
Split into simpler sentences: Mary Laughlin donated a block on June 6,1865, for use as site of the mint. In 1869, construction finally began with Harvey A. Hogue as the superintendent of construction.