Topaz Mountain is located about 40 miles West of Delta, Utah, at the Southern end of the Thomas Mountain range.
The road is paved all the way there, except fot the last 3 1/2 miles. It is then a light gravel road, with only a few rough spots, and those are only for maybe 20 feet.
You don't need a four wheel drive unit to get there. I have seen Cadillacs out there, but I think that they are a bit low to the ground myself.
Knowing how someone else's descriptions of where to turn, etc, can be a bit confusing, I have tried to be very descriptive, and if that isn't enough, I have inserted pictures of the major turns and intersections in the description below.
To get there take your favorite hiway toward Delta. I live in Salt Lake City, and Delta is about 145 miles South of Salt Lake. Topaz Mountain is about 165 miles South of Salt Lake (in case you are figuring out the math, the turn off to Topaz Mountain is North of Delta, so I don't go through Delta to get there). It takes me about 3 hours to get there.
Here is what I do (If this doesn't work for you because of where you live, just head to Delta, Utah):
I take I-15 South to Nephi, Utah.
I take the 2nd Nephi exit, and turn West and drive through Nephi on hiway 132.
I take hiway 132 West all the way to its end at hiway 6 at Lynndyl.
I turn left and head South on hiway 6 toward Delta.
OK, so now you are either heading South on hiway 6 near Delta, or you have driven to Delta, and are heading North out of Delta on hiway 6.
12 miles North of Delta (around mile marker 99), hiway 174 goes West. This is the only intersection between Delta and Lynndyl, so you can't miss it.
As if that weren't enough, there is a big brown sign if you come from the North, or a big green one if you come from the South, at this intersection.
The Brush Wellman plant here is right here too, and the InterMountain Power Project plant is about 10 miles to the West.
Turn West here onto hiway 174 (note your mileage here). After about 10 miles, you come to the InterMountain Power Project plant, and an intersection with a road that goes straight South to Delta. At this point, hiway 174 ends, and it becomes route 1954 (?), and the mile markers start over again.
After 5 or so miles, you will cross the Juab County line, and 15 miles off in the distance and to the right of the road, you will see Topaz Mountain. It is light grey in color.
Just after you pass mile marker 45 (you have driven about 38 miles from hiway 6), you will come to the turn off to the Topaz Mountain area. The turnoff is clearly marked with a large sign. (Note your mileage here).
Turn right (North) here onto the dirt road. After about 1/2 mile, you will come to an intersection with the old dirt hiway, and another sign pointing the way to Topaz Mountain. Go straight.
After 1.7 miles from the paved road, the main part of the road turns to the left (West), and a smaller brownish dirt road goes straight. Turn left (West) here. You will pass a sign telling you that only hand tools are permitted, and there is a pointed knoll in the background.
Continue west about 1/2 mile, and there is a metal pipe buried under the road, and a small hill to the left, and the road becomes rough for about 100 feet or so. If you think it is too rough for you, you can go around the hill and rejoin the road on the other side. I always just slow down and pick the best spot rather than go around.
Over the next half mile or so, several (about 3) small roads come in from the right (North). Keep going straight.
The road soon turns to the right (North) and heads toward Topaz Valley or Topaz Cove. You can see Topaz mountain wrap around the end of the cove about a mile ahead. The road becomes gravely here, and you should see topaz in the road shining in the sun or from your headlights (if it is dark). The roads from here on look like the bottom of stream beds.
After a few hundred feet, a small road goes off to the left; ignore it. Soon after, another road goes to the left. The road you are on and this road to the left parallel each other for about 1/4 mile or so and then rejoin. About 300 feet ahead, both these roads come to a camping spot between them. The current road comes to a rough spot at the camp spot, and the road to the left is usually in better shape. You may want to take it. You can camp here, but the next morning you will want to drive (or walk) about 3/4 mile further in to the actual "cove" or "basin" area, and this area is still in the open a bit for wind. I would keep going.
1/4 mile or so ahead, after the 2 roads have rejoined, the road turns to the left (West) again, and you aproach the "basin" itself. Just as it turns left, there is another camping spot (but I have always seen it occupied). You go through some narrow spots, but nothing too small for a Suburban. Through this whole area you are driving in the stream bed and other little stream beds join up, looking like smaller roads. Always stay on the biggest looking one, the others usually die out in 10-20 feet or so.
Just ahead, the road turns to the right (North), and there is a good camping spot on the left of this corner. I usually try to stay here. It seems more protected than the earlier spots. You are now only about 600 feet from where I like to gather topaz. You have now come only about 3.7 miles from the paved road.
Just about 100 feet ahead, the road turns left (West) again, but a small road goes off to the right and up a little hill and then ends. This goes right to the base of the hill that I like to work at.
Another 200 feet past here, and the road starts to get really bad. I have seen people with little toyotas continue for just a bit, but they are usually back in a while. There is quite a bit of flat ground on the left here for camping, but this is about the last place and it usually has larger groups. I only went past here once, but couldn't find anything appealing. But its worth a quick walk to see what its like.
You can look up into the end of the valley or cove from here. But I've never been there. Who knows, maybe thats where all the big ones are?
So back to the hill. This hill is on the North side of the road near the end here, and kind of sits in the bottom of the basin. This is where I usually do my stuff.
So now that you are here, how do you find all that topaz?