There is a $5 parking fee at the trailhead in addition to a $3 permit fee for each rider, or you can buy annual passes for parking ($50) and biking ($25) at all Georgia State Parks. Registration is required even if you have an annual pass. Since trails may be closed for maintenance or inclement weather, check with the Park Office to ensure availability.
From the mountain bike parking area, this steep trail descends 400 feet to the main camping area. There are a number of large (2-5") loose rocks in the trail and there will likely be small sticks and branches as well. The trail is kept clear of fallen trees, but since it doesn't get much traffic, the tree parts tend to stay strewn about all higgidly-piggedly. There are a couple of switchbacks that some might find difficult as they are filled with the previously mentioned loose rocks.
When you reach the main campground after about 1.0 mile, continue on the main (paved) park road around to the Fort Mountain Lake Loop and eventually (keeping right at the fork), reach the Trail 301 (East - West Loop)
The Goldmine Trail forms one of the "easier" recommended loops at the park. From the parking lot, the Goldmine loop initially follows Trail 301 (East - West Loop)
clockwise around the edge of park. When you reach the well marked intersection with 303 Goldmine Trail, turn right to go back to the parking area following the trail backwards from the route shown here. Many people won't find the climb back up to the parking area "easy" though.