What naturally occurring mineral fiber can pose health risks and is found in rock and soil?

The naturally occurring mineral fiber that poses health risks and is found in rock and soil is asbestos. Asbestos is a group of silicate minerals known for their heat resistance and tensile strength, which made them popular in insulation and building materials. However, when asbestos fibers are inhaled, they can lead to serious health issues such as lung cancer, asbestosis, and mesothelioma. This risk arises because the tiny fibers can become airborne and are easily inhaled, making exposure particularly hazardous in certain environments, especially during renovations or demolitions of older buildings.

In contrast, while lead, silica, and radon are indeed associated with various health risks, they do not fit the specific criteria of being a mineral fiber like asbestos. Lead is a toxic metal that can accumulate in the body and cause serious health effects, particularly in children. Silica is a compound that can become a health hazard when inhaled as fine dust leading to silicosis, but it is not a fiber in the same sense as asbestos. Radon is a colorless, odorless gas produced by the natural decay of uranium in soil and rock, which poses risks through inhalation but is not a mineral fiber.