Made of Silica Diatite patent no. 85018, Dec. 15, 1868 by  J.M. Merrick. Used in the James Whitcomb Riley house, 528 Lockerbie Street, Indianapolis, IN. Built in 1872. Shown below are pictures of the knob, rose and key hole cover on a door in the Riley house. Although the knob show little wear the source of the white surface coating is not clear. A well used knob is also shown. Click on each photo below to view additional images and information.