Logging Requirement:
1. Look at Anvil Mountain, the mountain visible directly north from GZ. COUNT how many gossans you see. Further, from that amount, how many seem to be a result of mining? Did you see yellow or orange stains in addition to the red?
Geology:
Gossans appear at veins or outcrops. "West of Silverton, the Mineral Creek drainage and the iron-stained flanks of Anvil Mountain are visible. Many mountainsides around Silverton are coated with red, yellow and orange minerals. These coatings (called gossans) were created by the ineraction of water and oxygen with iron-rich minerals in the rocks such as pyrite. This process was happening long before mines arrived in the region." (Matthews). Each stain color is the result of complex interactions between ores and their various forms. Each indicates that an ore is breaking down thanks to exposure and/or forces of erosion. See the references below for more information.
History:
During the 19th and 20th centuries, they were important indicators to prospectors who were looking for metal ores. Many practiced prospectors could view a gossan and tell what types of metal were available below the iron cap that was "bleeding" the color.
Historically, the term Gossan is a Cornish derivative meaning "blood hat." In the America's other terms were "iron cap" or "iron hat" from the german "eisenhut."
References:
Chronic, Halka. <i>Roadside Geology of Colorado</i>. 2nd ed. Missoula, MT: Mountain Pub., 2002. Print.
Matthews, Vince. Geology of the Durango-Silverton Train ROute. N.p.: D&SNGRR & Fort Lewis College, n.d. Print.
Wikipedia "Gossans." 6 July 2015.