About halfway between Eganville and Caldwell, just west of Searson Road, there is a wide spot in the roadbed visible from satellite imagery on Google Maps. The Eganville Leader (Leader p305) reported in 1950 that Algoma Steel had purchased the Radnor Mine near Perrault. When the mine was active, 50 years before, ore was teamed to a siding on the OA&PS. Near Perrault, at the end of Larmond Road (Larmond was the man who owned the property where the mine sat), there is a lake that looks like it could be a tailings pond; this wide spot in the roadbed is about the closest point on the line to the possible mine location.
In 1902, iron mines at Dacre were waiting to ship 10 000 tons of ore to Searson's Siding (Leader p16). The ore from Dacre was apparently better than that from Perrault, and both mines were hoping for a spur track.
Five miles east of Eganville, on Oliver Menard's land, the OA&PS quarried stone for bridge abutments and culverts. Blocks as large as 3'6" were made. Quarrying began 1894-05-01 under foreman PS Watson's direction. [Eganville Enterprise from Renfrew Mercury, 1894-09-07]. It is possible that this quarry was the same location as Searson's siding.