The Bitterroot Conglomerate
Newsletter of the Bitterroot Gem & Mineral Society
Vol. XXX issue 1
Presidents Column
2011 is here and I hope this message finds all of you in good health. Thank you for your vote of confidence in me for another year as president of the club.
One of this year’s tasks is to come up with a plan to provide programs and workshops that members have requested in learning more about. While at the same time other programs that are informative and interesting. Wayne Farley’s program on agates will be the first program of the year at our January meeting.
I’m hoping that we can also have the lineup of field trips, that we had last year, again this year. Steve, thank you. As members if you know of a place the club could go on a field trip this year please let me know.
At our January meeting I will have posters for our upcoming gem and mineral show in May. If you are traveling out of town or know a business that works with rock club related items please take a poster to them and ask to have them display it for us.
In this month’s new letter you’ll find a list of meeting dates and times for 2011. They have been set up with the church to hold our meetings again this year.
As for info on the field trips this year I hope to have suggestions on tools, clothing, useful equipment and other things to bring when we head out into the field. This information will be in the news letter for that outing. Club members, those of you that have been to one of the locations that we go to, if you could bring a specimen of what we will be looking for I would greatly appreciate it.
Take care for now and we hope to see you at the next meeting!
Mike
Editors Notes
We wish all a Very Happy New Year!
I want to thank Dianne and Mike for getting their reports to me early. I was hoping to receive reports from the committee chairpersons, but alas! Nothing yet. I notice, by reading Mike’s column, that he has a very ambitious desire for this year’s Club activities. I hope all will be willing and able to help with these various activities. I’m sure they will bring new life to the Club and form it into the best that the Club has been for many years.
I will need reports from the Chairperson of the various Committees during the last week of each month so they can be included in the newsletter.
The Editor is not responsible for the accuracy of articles accepted, items for sale, nor are the opinions expressed therein necessarily those of the Club Officers, members and/or the Club Editor.
Ralph
Christmas Dinner
Board of Directors
Club Officers
BGMS Minutes Dec. 4, 2010
The meeting was called to order by President, Mike Mc Connell. Following the Pledge of Allegiance to our Flag, the invocation was led by Ralph Luther. We had 36 Members and 2 Guests.
The purpose of the short meeting prior to our Christmas Pot Luck was to open to the floor and obtain further nominations for the Club Officers, Montana State Council Delegates, the Northwest Federation Delegates and the Board of Directors.
Since the last November meeting was cancelled due to bad weather the Club Officers were not elected. The nomination committee had nominated Mike McConnell for President, Dick Coppage for Vice President, Pam Myers for Secretary and Wayne Farley for Treasurer. Since no further nominations were offered from the floor it was moved, seconded and voted to elect those previously nominated.
Nominations for the Montana State Council Delegates were: Wayne Farley (who is currently the Council’s President), and Don Tibbs (who happens to be the Council’s Vice President)-we are in good company. Nominations were closed and both Wayne and Don were elected.
Nominations for the Northwest Federation Delegates were: Wayne and Dan Farley. The nominations were closed and both elected.
It was moved, seconded and passed to retain our current Board of Directors. They are:
Wayne Farley and Ralph Luther who will serve for the 2 year terms. Harvey Sharp and Steve Vieth were to serve for the 1 year terms. All have agreed.
The Installation of the New Officers for the 2011 Year were: President: Mike McConnell; Vice President: Dick Coppage; Secretary: Pam Myers and Treasurer: Wayne Farley. The Montana State Council Delegates were: Wayne Farley and Don Tibbs. The Northwest Feder-ation were: Wayne and Dan Farley. And, the Board of Directors were: Wayne Farley, Ralph Luther, Harvey Sharp and Steve Vieth. Thank You’s to Dianne Ayres for serving as the Secretary for 2 years were made and Dianne did the installation.
There being no further business a motion, second and passed to close the Business meeting and enjoy our WONDERFUL Christmas Pot Luck Dinner. The tables were loaded with such fantastic foods. Thanks to Pat and Don Tibbs for cooking the Turkey and Gene and Dianne Ayres for doing the Hams. ALL the rest was furnished by the Members. It was Delicious and complimented the festive decorations by Jenet McConnell and Pam Myers.
After eating, we all moved over to the front tables which were home for many great gifts brought for the Auction. Santa, Don Tibbs and his helper, Bob Riggs from the Missoula Club.
Door Prizes in the design of Center Pieces on each table (who were made and furnished by Jenet and Pam also) were given away. Then as a Grand Finale to the Auction, 2 Special Door Prizes furnished by Mike and Jenet McConnell were given to a lucky Man ( ?Dick Coppage ?) and
Woman, (Pam Myer). Thank You to the McConnell’s. Finally, our Rock of Gibraltar in the Kitchen – Sharlene Farley was given a round of applause for all her work during the entire year.
Anyone missing the Day was missed and hope that you will plan on coming next year..
Respectfully Submitted
Dianne Ayres,
Secretary
BGMS CABBING Mach.
Mike McConnell still has the machine. We hope we will see a product of his efforts with the machine at one of the next meetings.
Field Trip Report
None
Mining Committee Report
I have done a little research on opal in Idaho and find that there are more places in Idaho where opal has been found, more research needs to be done.
AGATES
By Wayne Farley
This program is all about Agates: the definition, the characteristics, the formation, the varieties, the history, and the uses of Agates. Approximately 50 different Agates will be shown to help explain the above.
What is an Agate?
An Agate is a matrix of the mineral chalcedony, a polymorph of Quartz (SiO2); and a variety of mineral coloring agents, mostly iron oxides and hydroxides, and manganese oxides. Polymorphs are minerals that have the same chemical formula, but different crystal structures. The crystal system of chalcedony is Trigonal; with the habit being fibrous clusters, tending to radiate perpendicular to the enclosing surface. Quartz is the second most abundant mineral in the earth’s crust, at about 12%; while Feldspar is the most abounded, at about 50%.
Chalcedony has been traditionally defined as a fibrous cryptocrystalline or microcrystalline variety of alpha-Quartz; but more recently, it has been shown that much Chalcedony is a mixture of microcrystalline alpha-Quartz, and Moganite (a polymorph of Quartz having a monoclinic crystal structure). Chalcedony usually contains about 5-15% moganite, but may contain as much as 25% Moganite. Moganite appears to change to alpha-Quartz over long geological time, and may be a coarse method of age dating chalcedony masses.
The web site http://www.quartzpage.de/chalcedony.html gives some significant properties of chalcedony as follows: “Chalcedony is a dense, more or less translucent, but never transparent and never opaque material. Pure chalcedony appears homogeneous and is white, gray or blue. When illuminated from the back, it may look slightly red. The blue and red tones found in pure chalcedony are caused by Rayleigh scattering of light on tiny particles, the mechanism that is also mostly[1] responsible for the blue color of the sky. More often, chalcedony contains inclusions of various minerals, which, if colorful, will taint the chalcedony. The cryptocrystalline varieties carnelian, chrysoprase, plasma and sard are all essentially chalcedony with different types of inclusions.”
When the Quartz/Moganite chalcedony mixture is concentrically banded, it is named “Agate”. Agate also has many variety sub titles depended on the configuration of the bands, or on the location where the Agate was deposited, e. g., Fortification Agate or Montana Agate.
When bands are in flat layers, it is called Onyx, Water-Level, or Uruguay-Type Agate.
In recent decades, some colored unbanned varieties of chalcedony have also been called Agate, e. g., Ellensburg Blue Agate, Carnelian Agate, Cloud Agate, etc.
The book “Gem and Lapidary Materials” by June Culp Zeitner (Ref. 13), and the web site by Roger Pabian (Ref. 15), have fairly complete listings of common Agate names and their descriptions.
What are the physical SiO2l characteristics of Chalcedony/Agate?
Composition: SiO2
Hardness: 6.5-7.0
Specific Gravity: 2.65
Refractive Index: 1.530 – 1.540
Fracture: Conchoidal
Crystal Formation: Cryptocrystalline
Color: pure is colorless, other colors depend on impurities
Translucency: Varies from extreme translucency to opaque
Streak: White
Test: Insoluble, unless placed in hydrofluoric acid
Luster: Waxy, Vitreous
Porosity: White bands - impervious, other bands - slight porosity
Melting Point: 1600* C, 2912* F
What is the history of Agate collecting?
Agates have been found in France with Stone Age artifacts dated back to 20,000-16,000 BC.
The earliest evidence of working with Agate comes from the ancient Mesopotamia fertile triangle, now occupied by Iraq), where many ornaments and tools have been recovered. The best known is an axe head of Agate with cuneiform writing on the side. It has been dated to the third millennium BC.
The Egyptians carved cups and bowls from Agate prior to 3000 BC.
Greek and Roman Biblical scholars and historians tell us that early Jewish high priests would don a breastplate with inlaid precious stones, one of the stones being agate (probably Sard).
Agates were also highly prized among many other ancient civilizations. It was fashioned into beads, pins, brooches, signet rings, goblets, cups, bottles, bowls, and carved figurines. Large amounts of agate have been found in archaeological digs of Sumer, dating back to 3500 BC.
The Greek Philosopher Tyrtamus (372-287 BC), nicknamed Theophrastus by Aristotle, was the first man to write about agates in his work “Concerning Stones”. In his writings, he notes that agate is a “marvelously beautiful stone” and usually sold at high prices.
The great Roman military commander Pliny the Elder (23-79 AD), was also a great writer of encyclopedias “Natural History” (science); and during the period 77-79 AD wrote 28 volumes concerning all of the natural science knowledge of his time. Included was a volume on precious stones and gems, which had a Chapter (54) on “Achates” (Agates). A translation of this work to English was included in the December BGMS newsletter. In this work Pliny the names the different varieties of Agate, where Agates are found, and list the spiritual and medical benefits of Agate.
Where does the name “Agate” derived from?
According to one version, the name Agate derives from the Achates River (now Dirillo River) in Sicily, where these stone were collected as far back as 3000 BC, and are still collected today. In another version, the name Agate comes from the Greek word “achates” meaning “happiness”.
How do Agates Form?
First, spherical openings form in Basaltic of Rhyolitic volcanic flows from expanding gas in extruded magma. When these rocks cool, the spherical openings are preserved. The solidified rocks may also later get linear openings from tectonic activities. At some point in Geological time, these spherical and linear openings get filled with silica (SiO2) saturated solutions; and after more geological time, these solutions crystallize and form various polymorphs of Quartz (Opal, Chalcedony, Moganite, Rock Crystal, etc.).
The next question is: where did the silica derived from, as Basalt and Rhyolite are low in silica. The most likely sources of the silica are from adjacent beds of high silica volcanic ash, or from the silica shells of marine sponges or radiolarians.
There are two main theories as how the silica crystallizes. The older theory is that the silica enriched solutions pass through the openings on a rhythmic basis; thereby depositing the silica layer by layer, starting from the outside of the opening, and progressing towards the center. The problem with this theory is, after each layer forms, how do additional solutions enter the cavity through the relatively impervious prior layers?
In a newer theory on Agate formation; after examining agates with electron microscopes; mineralogist discovered that Agates appear to have form at one time from a silica gel that filled the openings; and probably formed at a temperature of < 100 degrees centigrade. How then does one explain the rhythmic banding in Agates?
In 1896 the colloid chemist LIESEGANG found concentric banding in colloids, similar to agate banding, when he was experimenting with solutions of silver nitrate and potassium dichromate on gelatin gels. This showed that internal rhythms can build banding structures. The appearance of Liesegang-Rings in agates proves that silicates had a gelatinous stage before the ripening of the agate. Gelatinous silicate is commonly known as “water-glass. Further proof of a gelatinous formation of agates is that, deformable precursor of the agate show mainly exit channels in the agates. These exit channels are called Tubes of Escape, and often show Dilatation (dilation) features from excess pressure. Also, it is believed that hair Sagenites in agate would have required a supporting gel solution to have formed.
The outside of the agate nodule is commonly covered by a soft green mineral called Celadonite that is a breakdown product of the lava. This green outer coating is particularly well seen in agates newly removed from the host rock. Occasionally this outer coating can be red, brown or white, but all of these thin outer coatings are composed of material from the chlorite group of minerals.
What where some of the ancient uses of Agates?
The bow was used to drill holes into carnelian agate in Mehrgarh between 4th-5th millennium BC, thus enabling the ancients to wear agates as jewelry. Carnelian was recovered from Bronze Aga Minoan layers at Knossos on Crete in a form that demonstrated its use in decorative arts. This use dates to approximately 1800 BC. Carnelian was used widely during Roman times to make engraved gems for signet or seal rings for imprinting a seal with wax on correspondence or other important documents, as hot wax does not stick to Carnelian. Sard was used for Assyrian cylinder seals, Egyptian and Phoenician scarabs, and early Greek and Etruscan gems. The Hebrews odem (translated sardius), the first stone in the High Priest’s breastplate, was a reddish stone, probably Sard.
What are some of the modern uses of Agates?
Industry uses agates chiefly to make ornaments such as pins, brooches, paper knives, inkstands, marbles and seals. Because of its hardness and ability to resist acids, agate is used to make mortars and pestles to crush and mix chemicals. Because of the high polish possible with agate it has also been used for centuries for leather burnishing tools. In fairly resent times, knife edge agate was used to support the beam in beam balances.
References:
“The Book of Agates”, Lelande Quick, 1963
“The Agates of North America”, The Lapidary Journal, Hugh Leiper,1966
“The Agates of Northern Mexico”, Brad L. Cross, 1996
“Agates and Jaspers, Ron Gibbs, 2009
“Agates, Treasures of the Earth”, Roger Pabian, et al, 2006
“ The Beauty of Banded Agates”, Michael R. Carlson, 2002
“Understanding and Finding Agates”, Karen Brzy, 2004
“South Dakota’s Fairburn Agate”, Roger Clark,1998
“Fairburn Agate, Gem of South Dakota”, Roger Clark, 202
“The Lake Superior Agate”, Scott F. Wolter, 1994
“The Other Lake Superior Agates”, John D. Marshall, 2006
“Agates II”, Johann Zenz, 2010
“Gem and Lapidary Materials”, June Culp Zeitner, 1996
“Archaeo-Mineralogy”, Section 5.2.2, George (Rip) Rapp, 2009
Agate Data Base (Agate Photos by State/Country), Bibliography (4,682 Articles about Agates), Glossary (Ruin Agate, Chromatographs, Dilation, Faulted Agate, Pisolites, Pseudomorphs, Tube Agates), and Lexicon: (Agate Lexicon and Glossary of Agate, Jasper, Opal and other Amorphous, Cryptocrystalline, or Spherulitic Forms of Gem Silicon Dioxide). http://snr.unl.edu/data/geologysoils/agates/index-agates.asp
Agate Formation: http://www.agatesofscotland.co.uk/Agate%20Formation.htm
Thundereggs: http://en.wikipedia.org/wiki/Thunderegg
Chalcedony Gallery: http://www.mindat.org/gallery.php?min=960
Types of Agate: http://www.cst.cmich.edu/users/dietr1rv/agate.htm
Everything about Agates: http://www.cst.cmich.edu/users/dietr1rv/agate.htm
Agates With Inclusions: http://www.agateswithinclusions.com/
Best web source on Quartz, Agates, & Chalcedony: http://www.quartzpage.de/index.html Best technical book: “Dana’s System of Mineralogy”, Vol. III, Silicate Minerals, Clifford Frondel, 1962
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