The Agates of Scotland

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Symposium on Agate and Cryptocrystalline Quartz

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Symposium on Agate and
Cryptocrystalline Quartz
September 10 – 13, 2005
Golden, Colorado
Sponsored by Friends of Mineralogy, Colorado Chapter;
Colorado School of Mines Geology Museum;
and U.S. Geological Survey
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Cover Photos
{top left} Fortification agate, Hinsdale County, Colorado, collection of the Geology Museum,
Colorado School of Mines. Coloration of alternating concentric bands is due to infiltration of
Fe with groundwater into the porous chalcedony layers, leaving the impermeable chalcedony
bands uncolored (white): ground water was introduced via the symmetric fractures, evidenced
by darker brown hues along the orthogonal lines. Specimen about 4 inches across; photo Dan
Kile.
{lower left} Photomicrograph showing, in crossed-polarized light, a rhyolite thunder egg
shell (lower left) a fibrous phase of silica, opal-CTLS (appearing as a layer of tan fibers
bordering the rhyolite cavity wall), and spherulitic and radiating fibrous forms of chalcedony.
Field of view approximately 4.8 mm high; photo Dan Kile.
{center right} Photomicrograph of the same field of view, but with a 1 λ (first-order red)
waveplate inserted to illustrate the length-fast nature of the chalcedony (yellow-orange) and
the length-slow character of the opal CT LS (blue). Field of view about 4.8 mm high; photo
Dan Kile.
Copyright of articles and photographs is retained by
authors and Friends of Mineralogy, Colorado Chapter; reproduction
by electronic or other means without permission is prohibited


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Symposium on Agate and Cryptocrystalline
Quartz
Program and Abstracts
September 10 – 13, 2005
Editors
Daniel Kile
Thomas Michalski
Peter Modreski
Held at Green Center, Colorado School of Mines
Golden, Colorado
Sponsored by
Friends of Mineralogy, Colorado Chapter
Colorado School of Mines Geology Museum
U.S. Geological Survey
Meeting Chairs
Paul Bartos, Colorado School of Mines
James F. Hurlbut, Denver Museum of Nature and Science
Daniel Kile, U.S. Geological Survey
Thomas Michalski, U.S. Geological Survey
Peter Modreski, U.S. Geological Survey
Graphic Designer and Assistant to the Editors
Jeannine Honey
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Program
Friday, September 9
7:00 p.m. Welcoming reception, Colorado School of Mines Geology Museum
Saturday, September 10
7:15 – 8:15 a.m. Registration
8:20 Opening remarks – Paul Bartos, Curator, CSM Geology Musuem
Morning session I - chair, Paul Bartos, Colorado School of Mines
8:30 – 8:50 The nomenclature of crystalline, cryptocrystalline, and non-crystalline
phases of silica - Daniel Kile
8:55 – 9:15 Agates: banding and beyond - Roger K. Pabian
9:20 – 9:40 The beauty of banded agates - Michael R. Carlson
break 9:45-10:05
Morning session II – chair, Pete Modreski, U.S. Geological Survey
10:05 – 10:25 The agates and geodes of northern Chihuahua, Mexico - Brad L. Cross
10:30 – 10:50 Quartz family minerals (agate and amethyst) from Rio Grande do Sul,
Brazil, and Uruguay - Rock Currier
10:55 – 11:15 Clovis culture quarry sources and long distance movement of
cryptocrystalline lithic material on the great plains - Steven R. Holen
lunch break 11:20 – 1:00
Afternoon session I – chair, Tom Michalski, U.S. Geological Survey
1:00 – 1:20 p.m. Thundereggs: distribution and geologic setting - John Stockwell
1:25 – 1:45 Chalcedony occurrences in the central Great Plains - Roger K. Pabian
1:50 – 2:10 Australian agates and thunder eggs: why one is never enough - Penny
Williamson
break 2:15 – 2:35
Afternoon session II - chair, Paul Bartos, Colorado School of Mines
2:35 – 2:55 The Khur agate field, Central Iran - Maziar Nazari
3:00 – 3:20 Fluid inclusion analysis and manganese-iron oxide mineralogy of
quartz-chalcedony geodes from the Parana basalts, Rio Grande do Sul,
Brazil - Virgil W. Lueth and Philip C. Goodell
3:25 – 3:45 Seven causes of color in banded agates – Thomas C. Michalski and
Eugene E. Foord (deceased)
3:50 – 4:10 Very-high-temperature, closed-system origin of agates in basalts: a new
model, new and old evidence - Enrique Merino
4:15 – 4:35 Stratigraphic distribution, environments of deposition, and formation of
agate in the Buck Hill Volcanic Series, Brewster County, Texas - Andy
Zarins
break 4:40 – 4:50
4:50 – 5:30 Idar-Oberstein and its agate history - Renate Schumacher
5:35 end of session
6:00 Social “hour” at CSM Student Center
6:30 Banquet, CSM Student Center; Banquet Presentation: A history of
Scottish agates - Brian Jackson
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Sunday, September 11
8:00 a.m. Opening remarks – Dan Kile, U.S. Geological Survey
Morning session I - chair, Dan Kile, U.S. Geological Survey
8:05 – 8:25 Fairburn agate: occurrence in the badlands, grasslands and Black Hills
of southwestern South Dakota and northwestern Nebraska - Roger Clark
8:30 – 8:50 An American view of Scottish agates - Dale G. Wheeler
8:55 – 9:15 Structures and micro-structures in Scottish agates - Brian Jackson
9:20 – 9:40 Silicification of fossil wood - Richard Dayvault
break 9:45 10:05
Morning session II – chair, Tom Michalski, U.S. Geological Survey
10:05 10:25 Fluorescence of cryptocrystalline quartz and opal - Peter J. Modreski
10:30 – 10:50 Uraniferous opal, Virgin Valley, Nevada, contains evidence of its age
and origin – Robert A. Zielinski
10:55 – 11:15 Basal (c) face quartz, its history and occurrences - James F. Hurlbut
lunch break 11:20 – 1:00
Afternoon session I – chair, Jim Hurlbut, Denver Museum of
Nature and Science
1:00 – 1:20 p.m. Phenomena in agate: clues to its formation? - Si and Ann Frazier
1:25 – 1:45 The blue agate of Kittitas County, central Washington - Paul W. O.
Hoskin
1:50 2:10 Chalcedonies and jaspers used for carving - Helen Serras-Herman
break 2:15 – 2:35
Afternoon session II - chair, Dan Kile, U.S. Geological Survey
2:35 – 2:55 Thinking about thundereggs: An historical sketch of inquiry into their
nature and origin - John Stockwell
3:00 – 3:20 Ancient agate lore and early efforts to explain agate formation - Robert
Proctor
3:25 – 3:45 A review of "An Elementary Treatise on Quartz and Opal" by George
William Traill, 1870 - Beth Simmons
3:50 – 4:10 Chalcedony and unusual habits of crystalline quartz from carbonate
concretions in the Alberta badlands - Mike Menzies
4:15 – 4:35 Unusual quartz crystal growth habits - Jack Thompson
break 4:40 – 4:50
4:50 – 5:30 Creede sowbelly agate: banded amethystine quartz and chalcedony - Ed
Raines
5:35 End of session
Monday, September 12
8:00 a.m. Field trip to the Patch Mine (“Glory Hole”), Central City, Gilpin
County, Colorado; Dan Kile, USGS (Emeritus)
Tuesday, September 13
8:00 a.m. Field trip to North Table Mountain, Golden, Jefferson County,
Colorado; Pete Modreski, USGS
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Table of Contents
Color Plates: Images to accompany papers in this volume.........................................................7
The nomenclature of crystalline, cryptocrystalline, and non-crystalline
phases of silica - Daniel Kile.................................................................................11
Agates: banding and beyond - Roger K. Pabian.....................................................................14
The beauty of banded agates - Michael R. Carlson..................................................................19
The agates and geodes of northern Chihuahua, Mexico - Brad L. Cross.........................................20
Quartz family minerals (agate and amethyst) from Rio Grande do Sul, Brazil, and Uruguay - Rock
Currier..........................................................................................................26
Clovis culture quarry sources and long distance movement of cryptocrystalline lithic material on the
great plains - Steven R. Holen...............................................................................27
Thundereggs: distribution and geologic setting - John Stockwell.................................................28
Chalcedony occurrences in the central Great Plains - Roger K. Pabian..........................................30
Australian agates and thunder eggs: why one is never enough - Penny Williamson...........................34
The Khur agate field, Central Iran - Maziar Nazari........................................................................36
Fluid inclusion analysis and manganese-iron oxide mineralogy of quartz-chalcedony
geodes from the Parana basalts, Rio Grande do Sul, Brazil - Virgil W. Lueth
and Philip C. Goodell.........................................................................................53
Seven causes of color in banded agates – Thomas C. Michalski and
Eugene E. Foord (deceased).................................................................................60
Very-high-temperature, closed-system origin of agates in basalts: a new model,
new and old evidence - Enrique Merino...................................................................67
Stratigraphic distribution, environments of deposition, and formation of agate in
the Buck Hill Volcanic Series, Brewster County, Texas - Andy Zarins...............................71
Idar-Oberstein and its agate history - Renate Schumacher.........................................................73
Banquet, CSM Student Center; Banquet Presentation: A history of Scottish agates
- Brian Jackson.................................................................................................75
Fairburn agate: occurrence in the badlands, grasslands and Black Hills of
southwestern South Dakota and northwestern Nebraska - Roger Clark...............................82
An American view of Scottish agates - Dale G. Wheeler..........................................................87
Structures and micro-structures in Scottish agates - Brian Jackson...............................................89
Silicification of fossil wood - Richard Dayvault............................................................................95
Fluorescence of cryptocrystalline quartz and opal - Peter J. Modreski...........................................98
Uraniferous opal, Virgin Valley, Nevada, contains evidence of its age and origin
- Robert A. Zielinski.........................................................................................103
Basal (c) face quartz, its history and occurrences - James F. Hurlbut..................... .....................107
Phenomena in agate: clues to its formation? - Si and Ann Frazier...............................................109
The blue agate of Kittitas County, central Washington - Paul W. O. Hoskin..................................111
Chalcedonies and jaspers used for carving - Helen Serras-Herman.............................................116
Thinking about thundereggs: An historical sketch of inquiry into their nature
and origin - John Stockwell.................................................................................120
Ancient agate lore and early efforts to explain agate formation - Robert Proctor.....................................124
A review of "An Elementary Treatise on Quartz and Opal" by George
William Traill, 1870 - Beth Simmons.....................................................................125
Chalcedony and unusual habits of crystalline quartz from carbonate concretions
in the Alberta badlands - Mike Menzies..........................................................................126
Unusual quartz crystal growth habits - Jack Thompson...........................................................129
Creede sowbelly agate: banded amethystine quartz and chalcedony - Ed Raines..............................131
A proposed mechanism for the growth of chalcedony – Peter Heaney..........................................139

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Biologic crises and mass extinctions---The Lake Superior agate that formed in place in
volcanic rocks of late Precambrian age are an example of an abundant, widespread
occurrence of agates that takes place at about the same time in the earth’s history that there is
a considerable change in faunas.

During this time, the primitive Ediacaran faunas are giving
way to the shelly faunas of the early Cambrian. During the Devonian, the abundant agate
resources of Scotland formed at about the same time faunas changed from early to late
Paleozoic constituencies. The colonial animals, primitive mollusks and trilobites gave way to
echinoderm rich fauna, goniatite mollusks, and many trilobite families perished.

Many of the world’s largest agate occurrences are found the Permian-Triassic boundary, the
greatest mass extinction of all time. Many of the agates of Brazil, Germany, Poland,
Australia, and South Africa all are products of this time.

Agate formation continued on into
the Triassic as evidenced by extensive deposits along the eastern seaboard of the US, starting
in about North Carolina, and extending northeastward into New Brunswick and Nova Scotia
in Canada.

The extensive agate deposits of India are related to the Deccan basalts of late Cretaceous age
(Bose, 1908-1909, Officer and Drake, 1985), flows that some researchers think were caused
by the late Cretaceous impact that brought about the demise of dinosaurs, ammonites, and
hundreds of species of foraminifers.

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Conclusions---Agates may have considerable value and application to solving some modern
geological problems. They should receive the same attention that is shown to fossils and
other minerals and structures in providing evidence for interpretation of the earth’s history

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Baker Ranch = Geode Kid Baker eggs.