Mineral Content of Low Humic, Humic and Hydrol Humic Latosols of Hawaii

Data from X‐ray diffraction, elemental, differential and integral thermal, and infrared absorption analyses were used to characterize quantitatively the minerals in the clay fractions of representative soils of the Low Humic, Humic and Hydrol Humic Latosols of Hawaii. Allophane was identified in substantial amounts (approximately 30%) in the < 0.2u fractions of two Hydrol Humic Latosols. Other minerals present in the clay fractions of the Hydrol Humic Latosols include gibbsite (25–35%), goethite (10–35%), magnetite (5–20%), mica (1–10%) and quartz (0–3%). The Humic Latosol contained kaolin (15–20%), gibbsite (15–20%), hematite (20–25%), goethite (10–20%), montmorin (5–10%), interstratified 2:1 layer silicate (5–10%), mica (1–5%) and quartz (1–5%). The Low Humic Latosols were predominantly kaolinic (45–55%) with hematite (15–25%), allophane (5–10%) and montmorin (5–15%) in substantial amounts. The fractions < 2u constitute the major portion of the Latosols. All percentages given are of the < 2u fractions except that two whole soils are included with the Low Humic Latosol group.