McKinnan Gulch
Encyclopedia
McKinnan Gulch is a valley in Marin County, California
, United States
.
It contains a small stream which descends the western slope of the Bolinas Ridge
and drains into Bolinas Lagoon
.
Near the head of the gulch is an ore vein (reported in 1955) containing chalcopyrite
, galena
, pyrite
, and calcite
.
Marin County, California
Marin County is a county located in the North San Francisco Bay Area of the U.S. state of California, across the Golden Gate Bridge from San Francisco. As of 2010, the population was 252,409. The county seat is San Rafael and the largest employer is the county government. Marin County is well...
, United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
.
It contains a small stream which descends the western slope of the Bolinas Ridge
Bolinas Ridge
Bolinas Ridge is a north-south ridge in southwestern Marin County, California. Much of the western side of the ridge is protected parkland in the Golden Gate National Recreation Area, and the eastern side is watershed lands of the Marin Municipal Water District....
and drains into Bolinas Lagoon
Bolinas Lagoon
Bolinas Lagoon is a tidal estuary, approximately in area, located at in the West Marin region of Marin County, California, United States. It is a part of the Gulf of the Farallones National Marine Sanctuary. The lagoon is a back bay of Bolinas Bay on the Pacific coast approximately 15 mi ...
.
Near the head of the gulch is an ore vein (reported in 1955) containing chalcopyrite
Chalcopyrite
Chalcopyrite is a copper iron sulfide mineral that crystallizes in the tetragonal system. It has the chemical composition CuFeS2. It has a brassy to golden yellow color and a hardness of 3.5 to 4 on the Mohs scale. Its streak is diagnostic as green tinged black.On exposure to air, chalcopyrite...
, galena
Galena
Galena is the natural mineral form of lead sulfide. It is the most important lead ore mineral.Galena is one of the most abundant and widely distributed sulfide minerals. It crystallizes in the cubic crystal system often showing octahedral forms...
, pyrite
Pyrite
The mineral pyrite, or iron pyrite, is an iron sulfide with the formula FeS2. This mineral's metallic luster and pale-to-normal, brass-yellow hue have earned it the nickname fool's gold because of its resemblance to gold...
, and calcite
Calcite
Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate . The other polymorphs are the minerals aragonite and vaterite. Aragonite will change to calcite at 380-470°C, and vaterite is even less stable.-Properties:...
.