||Between Lebanon and Brickerville on US 322, 2 miles West of Brickerville. From Turnpike Exit 20 and Rt. 72: Follow 322 towards Ephrata. Go about 4-5 miles. Eventually you'll come down a long downhill. Close to bottom, there's a Game Commission parking lot is on left, and a stream is adjacent to the lot. If you look (face due north) between the main road (322) and the dirt road the climbs are 100 yds up the small hill. The rock is visible in the winter from 322, yet disguised very well in the summer.
*** Recently, as I drove down 322 I spoted another significant outcropping about 100 yds behind the first outcropping, I've never checked it out, but it looked worth while.
There is an additional spot called the Potato Patch (diabase boulders!) continue north east on 322 for about a mile to a small pullout on the right. Follow obvious trails across the creek to wash of diabase boulders.