I dont think Charlie was yakima tribe. He got interviewed and claimed he wasn’tThe documentation of this story is weak. Ruby El Hult has a retelling of this story in her book, "Lost Mines and Treasures of the Pacific Northwest." We don't know if the mine was a hard rock, placer, or a pocket.
According to the story, the miner whose name is unknown would travel down the Klickitat Valley on his way to the Dalles. He would cash in his gold at the French & Company Bank. The dates for this story are uncertain but thought to be sometime in the 1880s. It is possible that the mine was actually an Indian mine, located on the Yakima Reservation. The miner disappeared and it is unknown what happened to him. Skeletons of a man and pack animals were found East of Spirit Lake. It could have been what happened to the miner. In 1922, Charlie Wannassie of the Yakima tribe offered to sell the secret of the "Spanish diggings", but it unknown if anyone took him up on the offer. Like a lot of lot mine stories, the quantity of gold is always exaggerated.
A large area around Mt St Helens was obliterated by the May, 1980 volcanic eruption. Millions of tons of ash covered the landscape and changed the topography of the areas around St Helens and Mt Adams. There were places in Eastern Washington where the ash was over a foot deep, and the ash was carried across the entire United States. Rivers and streams in the area were permanently changed. It is my opinion that search for this lost mine is a waste of time.
There are gold veins and pockets in the coastal mountain ranges from Central America to Alaska. The best chances of a new discovery are in areas that have already produced gold in the past. Some of the best areas are already under claim or have been withdrawn by our Government. It is very expensive to develop a hard rock mine, and there is a lot of red tape and compliance. The hobby miner has a much better chance of finding and working a placer deposit. Black sand deposits along the entire length of the Lewis River contain flower gold. The lucky prospector may find some good sized nuggets in the headwaters of the river. Prospecting on the Yakima Reservation is prohibited.