Black coral, shells, and hobby-collecting material 42 Construction materials 43 Coral, beach sand, and limestone 43 Crushed basalt _ 44 River sand and gravel 44 Volcanic cinder 44 Gypsum ... .......... 45 Iron 45 Plastic clay _~ 45 Surficial deposits _ 45 Occurrence 45 Description 46 Mineral composition ___ 47 Chemical composition 48 Origin ...__ ....___... 49 Resources 50 Firing tests and appraisal.... 51 Buried deposits 53 Peat 55 Surficial deposits __. 55 Buried peat _..______ 55 Salt _-. .__. 55 Titanium ~_. 55 Reconnaissance of ferruginous bauxite deposits on Maui _ __ ___._ .____-___ ____ 56 West Maui ____._______._____ _______. 56 Volcanic rocks associated with bauxite 56 Sections and partial mineral-content estimates of weathered parts of the Wailuku and Honolua Volcanic Series 58 Economic geology ~_. . .__

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Introduction Definitions Types of deposits Hydrothermal Residual Sedimentary United States History and production Sedimentary deposits Atlantic and Gulf Coastal Plains-South Carolina-Georgia-Alabama kaolin belt-Location Occurrence and age Arkansas bauxite region Other districts in the Coastal Plains Districts in North Central and Western United States

The term bentonite is defined as any natural material composed dominantly of the clay minerals of the smectite group and whose properties are controlled by these clay minerals. Fuller's earth refers to naturally occurring material that has a high absorptive capacity. Both bentonite and fuller's earth have a wide variety of physical properties that make them suitable for many commercial uses and applications. The sodium or Wyoming bentonite is a high swelling variety used in drilling muds, bonding foundry sand, and pelletizing taconite iron ores. The calcium or southern bentonite is a low or nonswelling variety used for bonding foundry sand where a highstrength green bond is required. Large amounts of fuller's earth are utilized to make granules that are used as an absorbent for oils, grease, chemicals, as an animal litter, and as a soil conditioner. Almost all of the commercial deposits of bentonite and fuller's earth are in geologic formations that are either Cretaceous or Tertiary in age. Bentonite occurs in Tertiary rocks in the Atlantic Coastal Plain, the Gulf of Mexico Coastal Plain, and in the Mississippi embayment. The best grade swelling bentonite occurs in the Mowry Shale of Cretaceous age in Wyoming and Montana. The most abundant nonswelling bentonite is found in Tertiary formations of the Jackson and Claiborne Groups in Texas. An important geologic unit for fuller's earth deposits is the Tertiary Hawthorn Formation of Georgia and Florida. In 1988, almost 75 percent of the bentonite production in the United States came from Wyoming. Alabama and Mississippi together produced about 14 percent; California produced about 4 percent, and Arizona, Texas, and Utah each produced about 1 percent. States producing less than 1 percent of the U.S. bentonite were Colorado,

Abstract-Inorganic gel and allophane collected from basaltic saprolite on Maul, Hawaii, and studied by Patterson in I964 were reexamined. The main constituent of the gel is imogolite, and gibbsite and allophane are the minor constituents. Electron and X-ray diffraction patterns, DTA curve, and an infrared spectrum of the gel are characteristic of imogolite. The allophane is virtually noncrystalline to X-rays but contains a small amount of imogolite in relatively short threads. High-resolution electron micrographs indicate differences in structural organization between allophane and imogolite and suggest crystallization of imogolite from allophane.The occurrence of imogolite as a weathering product has been reported in many localities from pyroclastic materials but not from massive rocks. Probably the exceptionally high rainfall, excellent subsurface permeability of the weathered material, and the low pH and high organic content of the leaching solution provide favorable conditions for formation of imogolite from basalt on Maul.