Paragonite is a dioctahedral mica that contains Na rather than K in the interlayer position, but is otherwise virtually identical to muscovite. Reports on the occurrence of paragonite in soils are rare, and its influences on soil properties and pedogenesis are not well characterized. Paragonite was identified in soils derived from quartzmica schist landslide colluvium at elevations between 670 and 2010 m in the Klamath Mountains of northern California. X-ray diffraction (XRD) peaks from rock samples and sand, silt, and clay fractions of the soils match characteristic d-spacings of 0.962 nm for paragonite and 1.00 nm for muscovite. Paragonite:muscovite XRD peak height ratios indicate that the amount of paragonite relative to muscovite is lowest in the silt and clay fractions of the most weathered soil horizons, perhaps as a result of dilution when inherently larger muscovite particles are comminuted. Energy dispersive spectroscopy revealed the presence of both Na and K in micaceous grains. Paragonite and muscovite apparently are intimately associated, but variations in d-spacings indicate limited substitution of K in paragonite and Na in muscovite. X-ray diffraction, rather than optical microscopy, is required to distinguish between paragonite and muscovite.