Black Mountain is located in north-central Maricopa County, Arizona, between the towns of Carefree and Cave Creek. The mountain is composed of two main rock types that are roughly divided between western and eastern halves of the mountain. The west side of the mountain is composed of a ~250 m. bed of meta-sedimentary rock di…Black Mountain is located in north-central Maricopa County, Arizona, between the towns of Carefree and Cave Creek. The mountain is composed of two main rock types that are roughly divided between western and eastern halves of the mountain. The west side of the mountain is composed of a ~250 m. bed of meta-sedimentary rock distinguishable as phyllite and argillite. From a distance, the meta-sedimentary rock is easily mistaken for basalt, which is common in the area, however basalt is not found on Black Mountain. The phyllite has a slaty cleavage and is foliated in all directions, a result of shortening due to pressure-solution volume-diffusion of as much as 50%. As a result of shortening, streambeds of nearby washes are filled with black alluvium.
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