Some of Hayden Hill’s history is fairly well documented, and others aspect hardly nothing. One of the Hill’s most important operations were the cyanide tanks, used to leach the gold from the crushed rock. It was such an integral part of the mines, yet references are almost non-existant, and then quite void of hardly information. It is interesting to note the cyanide tanks from the early mining days were still there in 1962.
During the 1990s, when Lassen Gold revived mining at Hayden Hill, cyanide was also used. Even though Lassen Gold shut down in 1997, the wells there are monitored for any cyanide leakage.