Samuel Smith built a mill here in 1742. Henry Bates Grubb bought the property in 1800 and founded the Mount Vernon Furnace. Milling operations ended in 1913. Today, the ruins can still be seen at the Moonstone Manor wedding venue. (https://www.moonstonemanor.com/)
| Built | c1832 |
| Structure | 2.5 Story Stone |
| Dimensions | 40 x 60 |
| Water Source | Conewago Creek |
| Township | West Donegal |
| Type | Flour/Grist/Saw |
| Headrace | 300 feet |
| Tailrace | 100 feet |
| Dam Height | 10 feet |
| Power | 1 Overshot |
| Capacity | 8 bbl /day |