Agates Inside Out
Table of Contents
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Dedication
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vi
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Acknowledgements
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vii
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Introduction
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viii
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Chapter 1: What is an Agate?
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1
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A Basic Description
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1
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Agates and Human History
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2
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Agates and Their "First Cousins"
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4
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Macrocrystalline Quartz
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4
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Fibrous Microcrystalline Quartz
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8
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Granular Microcrystalline Quartz
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9
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Silicified Fossils
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10
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Quartz Properties
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14
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Chapter 2: How Did Agates Form?
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16
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The Earth - In the Beginning
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16
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Agate Formation
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21
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Inflow Agate Genesis Theory
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24
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Possible Sources of Silica
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28
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Silica Transport
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31
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Infiltration Channels
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34
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Concentric Banding
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41
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Horizontal Banding
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55
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Silica Gel Agate Genesis Theory
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57
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Agate Genesis Conclusions
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60
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Silica Gel Theory
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60
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Inflow Theory
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62
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Types of Host Rock
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65
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Igneous Rock Agates
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67
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Amygdaloidal Agates
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67
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Rhyolitic Agates
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70
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Sedimentary Rock Agates
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73
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Timing of Agate Formation
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76
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Chapter 3: How Do You Find Agates?
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82
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A Pocket Filled In
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88
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Banding and Other Patterns
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90
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Translucency
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93
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Color
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95
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Shape, Size, and Weight
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106
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Luster
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109
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Husk
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112
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Connective Channels
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118
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Pseudobands
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120
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Agate-Want-to-Be
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122
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Chert, Flint, and Jasper
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122
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Metamorphic Rocks
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126
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Secondary Fills
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127
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Silicified Fossils
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128
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Other Agates-Want-to-Be
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132
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Caring For and Cleaning Agates
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135
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Assessing the Value of Agates
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138
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Chapter 4: What Are the Different Types of Agate?
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139
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Botryoidal (Grape) Agates
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139
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Brecciated (Mosaic) Agates
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140
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Candy Striped Agates
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141
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Carnelian Agates
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142
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Cloud Agates
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144
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Crazy Lace Agates
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144
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Dendritic Agates
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146
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Enhydro (Water-Filled) Agates
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150
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Eye Agates
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151
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Fire Agates
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156
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Flame Agates
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158
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Floater Band Agates
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159
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Fortification Agates
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159
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Geode Agates
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161
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Iris (Rainbow) Agates
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162
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Jasper Agates
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165
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Moss Agates
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165
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Paintstone Agates
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168
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Peeler Agates
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168
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Plume Agates
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170
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Polyhedroid Agates
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172
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Pseudomorph Agates
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173
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Ruin Agates
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174
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Sagenite Agates
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175
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Sardonyx
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177
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Seam Agates
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178
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Shadow Agates
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180
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Stalk Aggregate Agates
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182
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Thunder Egg Agates
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182
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Tube Agates
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184
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Water-Level Agates
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186
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Chapter 5: Where Can You Find Agates?
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187
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A Selection of United States Agates
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187
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California
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190
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Florida
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191
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Idaho
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192
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Iowa
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193
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Kentucky
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194
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Michigan
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196
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Minnesota
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198
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Missouri
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200
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Montana
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201
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New Mexico
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203
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Oregon
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204
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South Dakota
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207
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Texas
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210
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Wyoming
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211
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A Selection of International Agates
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212
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Argentina
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212
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Australia
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215
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Botswana, Africa
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216
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Brazil
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218
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Canada
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220
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Caribbean
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223
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China
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225
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Mexico
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227
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References
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231
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Index
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239
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Museum Information
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243
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How to Vote for Your Favorite Photograph
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244
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Information About Agate DVDs and Other Products
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244
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Rock Hunting Log
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245
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