Home Return Button

Introduction and Background. 5

What is a Lake Superior Agate?. 6

Gel Chemistry. 7

Help!  I just realized all agates do not form in lava voids! 13

General Discussion of Inclusions. 17

Banding Systems. 21

Overview of the Geologic Conditions of the Lake Superior agates. 23

Clays in the World Ocean. 29

Geodes versus Amygdules. 32

The Great Cretaceous Lake Superior agates. 33

Glacial Extent of the Lake Superior Agates. 35

Keweenaw Peninsula Mineralization. 36

Copper Alternating Precipitation with Agate. 37

Where oh where did the Keweenaw Celadonite go?. 44

Volcanogenic Massive Sulfide (VMS) Deposits of the Canadian Shield. 46

Temperatures of Agate Formation. 49

Supercritical Water. 51

Supercritical water—halloysite. 56

Limitations of X-ray Spectroscopy. 57

Amethyst 58

Anhydrite pseudomorphs (quartz “cubes”) 59

Axiolites. 64

Banding Systems. 65

Banding—axiolitic banding. 65

Banding—chevron banding. 66

Banding—compressed banding. 67

Banding—compressional banding. 69

Banding—disrupted banding. 70

Banding—fortification agate. 70

Banding—illite microspheres and microdiscs. 74

Banding—iris banding. 75

Banding—pinched banding (pinched fortification) 75

Banding—shadow agate. 76

Banding—spiny illite (hairy illite) banding. 76

Banding—swirled banding (hurricane, disrupted banding) 79

Banding—wall-banding. 82

Barite. 82

Boiling Structures. 83

Boiling Structures—hemispheres. 83

Boiling Structures—banding hemispheres. 84

Boiling Structures—tee-pees. 84

Breccia. 86

Breccia—lamellar breccia. 87

Calcite. 88

Calcite—dogtooth calcite. 88

Calcite—impressions. 90

Calcite—pseudomorph. 91

Calcite—rhombohedral perimorph. 91

Calcite—scalenohedral calcite. 93

Candy stripers (illite-hematite) 94

Celadonization. 94

Cherts. 95

Chlorite. 96

Chlorite—curls. 96

Chlorite—Fe, Mg, SO4-Chlorite. 97

Chlorite—Fe, Mg-Chlorite with coronas. 99

Chlorite—Mg, Fe-Chlorite in a banding system.. 101

Chloritoid. 102

Clay Minerals. 102

Clays—coronas. 105

Clays—crenulated banding. 106

Clays—halloysite. 108

Clays—halloysite above calcite. 111

Clays—halloysite adsorption. 112

Clays—orbicular halloysite. 113

Clays—hydration structures. 113

Clays—illite clay (moss agate) 114

Clays--imogolite. 117

Clays—nontronite. 118

Clays—palygorskite (attapulgite) 120

Clays—vermiculite. 123

Clinopyroxene (diopside) 124

Cristobalite/Andalusite. 124

Datolite. 127

Dendrites. 129

Dissolution Structures. 130

Eye Agate. 131

Geodes (Lithophysae) 133

Gilsonite (Organic Carbon) 134

Hematite. 136

Hematite—goethite. 136

Hematite—hematite-sericite. 137

Hematite—specular hematite. 139

Implosion (Hash) 139

Jasper (Jasper-Agate) 140

Jasper-Copper. 141

Metamorphic Mineralization (Metabasalt) 142

Olivine and Rhodochrosite. 143

Oolitic Agate. 144

Opal 145

Paint Agates. 145

Plumes. 147

Prehnite. 149

Prehnite--acicular. 149

Prehnite--tubes. 153

Pumpellyite. 154

Pyrophyllite. 155

Quartz. 156

Ruin agate (mosaic agate) 157

Rutile-Calcite-Quartz. 157

Sagenites. 158

Sheared Agate. 161

Shell Tubes. 162

Skip-‘n-Atom Agates (Sericite-Quartz) 168

Striated Agate (Tremolite) 170

Sulfides. 171

Waterlines. 173

Waterlines (water levels) 173

Waterlines—waterline intrusions. 174

Wüstite. 175

Zoned Mineralization. 178

Commonly Asked Questions about the Agates. 179

Conclusions. 180

Further Reading. 181

Kasper Jasper Press Titles. 182

 

Home Return Button