Its true, the beaches of Lake Superior have gold deposits in them that can be found. We have heard reports of finding 20+ colors in a single pan of gold. The gold that is found in Michigan is Placer gold that is left over from the last ice age when Michigan was covered in Glaciers.
If you want to find the highest concentrations of gold on the Beach go to the mouth of the Two Hearted River and head West to Grand Marais. This entire section of beach has gold in it. Look for the bands of black sand and test them. When you find a good section of black sand that has a high amount of colors in it that is where you need to look. Remember that the waves push the water lateral to the shore and the sand is moved in the same motion. This creates areas of very high concentrations of gold in the black sand.
I have also heard of Gold Nuggets being found further south in Michigan near Grand Rapids on the Rogue River. This area has gravel mines and this river travels between them. The Rogue River passes thru an area of a terminal moraine from the last glacial ice age so it makes sense that there would be gold nuggets there. As far as beach sand goes Lake Superior East of Grand Marais is perhaps the best place in the country (with the exception of Alaska) for beach mining.
Another place for looking for gold is Dawson Creek in Michigan's Upper Penninsula. I have heard of small dredges operating in the back country here getting good amounts of gold in their sluice. Be careful when you go prospecting in the upper penninsula or on Lake Superior, Michigan has some strange laws on what is legal and what is not. Also, the miners and dredgers dont want to be bothered and can get very possessive of where they are working. This is an area of the Upper Peninsula where there is little population except for Campers in the summer. The tourism industry doesnt want to promote the fact you can find gold because weekend miners would quickly go there and destroy our natural wonders and probably hurt the spawning pattern of some frog. Remember the days when you could have fun without getting in trouble with the law for bothering some small fish.
Michigan has lots of abandoned Gold Mines across the state most of which are in the Marquette Range from Marquette to Champion to Skanee. I cant confirm it but I have heard of miners working in the woods here and finding good deposits of gold. It will be really interesting to see as the price of gold continues to increase if some of these mining areas of the past will be reopened to commercial gold mining right here in Michigan.