He came from a politically prominent American family and was a descendant of George Mason, a framer of the U.S. Constitution and father of the Bill of Rights.

Upon the death of his father, he and his siblings frequently squabbled over the division of the estate and the profits made by selling enslaved men and women.

In 1823, Richard complained to his brother George that "I wish you would make some exertion to pay me for Tom Clarke [an enslaved man whom the family sold].

Like so many other enslavers and prominent Virginians, Mason's wealth was heavily dependent upon the labor and bodies of the people he held as slaves.

In 1820, he told his brother to "advise Gerard by all means to sell his landed property and move with his Negroes to KY or the Missouri."

Barnes frequently complained to his siblings about his low pay, and implored them to send his money or his "negroes" so that he could work them in Kentucky.