The Bitterroot Conglomerate
Newsletter of the Bitterroot Gem & Mineral Society
Vol. XXIX issue 3
Presidents Column
I hope that everyone is doing well. Thank you to one and all that made it to the February meeting. I know the business portion of the meeting went longer than I planned but I feel there were a number of topics that were addressed and progress was made. Our show in May is approaching fast if you have ideas or can help the show in anyway please let Steve Vieth or I know.
The Spokane show is March 12th, 13th and 14th at the Spokane Fair and Expo Center. My wife and I are looking forward to the show and I hope as many that want to go, can make the show as well.
I will be on vacation for the March 23rd meeting and Pam will be in charge. Everyone have a great spring and I’ll see you in April. --- Mike McConnell
Editors Notes
This is the month that we travel to Spokane to their great Gem & Mineral Show. We leave early; 7AM from Lolo Harvest Foods parking lot and 8AM from the Kmart parking in Missoula. It should be a nearly full bus because of the good turn-out this year.
I will need reports from the Chairperson of the various Committees during the 1st 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.
BGMS Minutes (none for last month)
Labeling and Cataloging
Rocks, Minerals, and Fossils
Why ? !
You went on a field trip and found a wonderful specimen that you and the folks you were with could not identify in the field. You had some tantalizing suggestions and carefully brought it home, along with a detailed description of where you found it and what minerals were around it. And after two weeks of working through every test in all your fieldbooks, you finally decide it must be Leaverite and put it on the shelves with the rest of your collection.
Fast forward too many of years.
You died in an earthquake when your rock collection was shaken off the shelves and collapsed your house as it hit the floor. Your kids are settling your estate and selling off or claiming what you left behind according to your Will. They come to your rock collection. How are they going to identify the rare specimen of Leaverite that your Will says they should donate to the Smithsonian because the write-off will eliminate all the estate taxes?
Duh! The specimen was properly labeled. And please forgive me for the horrible drama.
Labeling
Labeling should have two parts; marking the stone with an identifier, and creating a label with the same identifier and the significant details (recording of all the details is left for the catalog, connected by the identifier). The identifier is nothing more than a serial number, but allows you to connect stone and label (and catalog) should they ever become seperated because the same, unique number is on each.
A label is typically something like a blank business card that has been folded in half to the shape of an L. The part that sticks up has the name of the mineral and where it was collected written on it, along with the identifier for the specimen. A label might look like
The catalog entry (more below) contains the identifier.
The stone itself has the identifier attached to it. There are many ways to do this.
- Be traditional and scribe the identifier on the rock with India Ink and a fine point. As a variation, put a dot of white paint on the rock first.
- Write the number on a self-sticking label and stick it on the rock.
- Write the number on the rock with a permanent, fine point, felt tip marker (like a laundry marker).
- Write the number on a piece of masking tape and stick it to the rock.
- Write the number on a piece of paper, cut it out, and stick it to the rock with glue. To do this, put a drop on a flat spot, and push the label onto the drop.
- Write the number on a piece of paper, cut it out, and stick it to the rock with clear shellac or (poly)urethane. To do this, put a drop on a flat spot, and push the label onto the drop. If the surface is uneven, you may need to add a drop to the top of the label too. The clear finish is adsorbed thru the paper, sticks to the rock, and makes a permanent, waterproof, identifier.
The identifier is nothing more than a sequence number; 1, 2, 3, 4, 5, etc..
Cataloging
A catalog is a list of all the rocks you have in your collection, along with their identifier and all details about them. You probably know more about each rock you have than will fit well on a label, and a catalog gives you a place to keep this information. Your catalog may be nothing fancier than a stack of index cards, or it might be a computer database.
Each catalog entry will contain the label information, the identifier, and additional details such as when found, full details of where found, the chemical formula, associated/secondary minerals identified, and for larger collections, where the specimen is physically stored. It might also contain pictures of the specimen and the field trip you collected it on, what identification tests you performed, and a list of what shows you have displayed it at. And if your specimen was purchased, the details of the purchase and everything from the original label would be included.
Opal
Figure 5 -- Contra luz opal from Oregon.
(Photo is courtesy of Kevin Lane Smith.)
Opal is brittle, heat sensitive, and breaks and scratches easily; additionally, some varieties self- destruct through the loss of water. Even with these drawbacks, opal's unsurpassed beauty guarantees its status as a premier gemstone. The derivation of its name even adds to its position. Reportedly, opal's name evolved from the Roman word opalus from the Greek word opallios meaning "to see a change of color." The Greek word was a modification of the ancient Indian Sanskrit name for opal, upala, which meant "precious stone." If one spoke in mixed tongues, then opal would be opallios upala, "to see a change of color precious stone."
As indicated by the derivation of its name, opal has centuries of history as a treasured gemstone. Historically, beliefs associated with the wearing of opal have varied. The early Greeks thought that opals gave their owners the powers of foresight and prophecy, and the Romans adored it as a token of hope and purity. Eastern people regarded it as sacred, and Arabs believed it fell from heaven. In the nineteenth century, superstitions grew about the bad luck or fate that could befall one for wearing opal if it were not the wearer's birthstone. Today, these superstitions have diminished, but some people still believe it is bad luck to wear opals.
Opal has over one hundred variety and trade names, but the list of accepted or commonly used names is much shorter. The most important and most widely known opal is the precious opal. Precious opal may be subdivided further by color modifiers, white, black, pinks, and blue, which describe the body color of the opal. Australia is famous for its white and black precious opal. Fire opal, the bright red, reddish-yellow, orange, or brownish-red body colored opal is the second most important opal commercially. Until recently, the best fire opal came from Mexico.
Arizona.--Two commercial mining operations in Arizona produce blue precious opal. The body color is a light or pale blue with strong play of color in red, blue, green, and orange. The two operations sell most of its material as finished stones at the Tucson Gem and Mineral show and other local gem shows.
Idaho.--In Idaho, opal is the second largest contributor to the total value of gem material produced. The varieties produced include precious (white and pink), yellow, blue, pink, and common. The Spencer opal mine, the largest privately owned gem stone producer in the State, is the major producer of opal. At Spencer the precious opal occurs as one or more thin layers within common opal partially filling gas cavities within a rhyolite-obsidian flow. About 10% of the material is thick enough to cut into solid gems; the remainder is fashioned into doublets and triplets. The Spencer Mine is the source of pink common opal and pink precious opal.
Louisiana.--The reported precious opal from Louisiana is a sandstone/quartzite with precious opal cement and matrix. It has blue or purple play of color. The material could be cut into cabochons for jewelry and other items of interest. To date, most of the material has been cut into large (over 2-inches in diameter) gemstone spheres.
Nevada.--Nevada is known for precious opal from Virgin Valley. The first discovery of precious opal in the Virgin Valley area was in 1905 or 1906. Since then a significant quantity of the highly prized opal has been recovered. Virgin Valley opal is comparable to any in the world for its vivid play of color and in terms of the size of material available. Individual pieces weighing over 3 kilograms have been recovered from the Virgin Valley deposits. In 1993, miners found a 100-kilogram opalized log containing precious opal. The material varies in body color from deep pure black to brown to yellowish-white to white to colorless. The play of color includes all colors common to precious opal, red, blue, green, yellow, orange, etc. The opal occurs primarily as replacement of wood, or sometimes, as replacement of conifer cones. Some opal does occur as nodules filling void spaces in clay. The wood replacement is so complete, that generally the wood grain and banding are no longer visible. The exception to this would be that often the exterior wood texture is still present as a brown or black rind.
The uses of the opal can be restricted because of crazing. Crazing is the breakdown or deterioration of opal by the development of very fine cracks all over the surface that extend until they intersect. In the worst cases, the surface of the opal deteriorates into a crumbling sand-like material. Because of the crazing the opal is not well suited for use in jewelry, but displayed in water, glycerine, mineral oil or other liquids makes remarkably beautiful mineral specimens. The mineral collections of most of the better museums contain very fine pieces of Virgin Valley opal. Many museum pieces are crazed from exposure to the air.
During the summer months, at least two dig for fee mines in Virgin Valley are open to individuals. One mine is operated by the Hodson family and the other by the Wilson family. Individuals pay a daily fee to dig and keep all the opal that they find. Other mines in the area are commercial opal producers.
Two other locations in Nevada also have produced precious opal. The opal does not have as good a play of color as that from Virgin Valley and it has the same crazing problem. One location is south of the Virgin Valley in the Calico Mountains of Humboldt County, and the other is near Gabbs in Nye County. The three precious opal locations and many other locations around the State produce common opal and opalized wood.
Oregon.--During 1988, West Coast Gemstones, Inc., began mining and marketing a variety of very fine-quality opals from Opal Butte in Morrow County, OR. The varieties produced includes hyalite, rainbow, contra luz, hydrophane, crystal, fire, blue, and dendritic. Exquisite stones as large as 315 carats have been cut from contra luz rough from this deposit.
The deposit at Opal Butte has been known since the late 1800's. It was of interest only to hobbyists until recently because people believed most of the opal was unstable. Stability can be a problem with the opal, crazing can occur when stresses are created from shrinkage due to water loss. West Coast has developed methods of drying the opal that greatly reduce crazing. Even with the drying procedures, the stability varies from 20% to 90% depending upon the variety.
The opals are found in rhyolite geodes (thundereggs) in a perlite that has altered to a pastel colored clay. The geodes that contain gem-quality opal are only about 10% of the total geodes mined and only about 1% of the geodes contain gem-quality opal with play of color. The remaining geodes contain agate, quartz crystals, or common opal. The geodes vary greatly in size, from a few centimeters in diameter to over a meter.
The deposit continues to produce a supply of very fine quality opal for cutting and carving. Currently, a company has launched an American gemstone jewelry line based on the Opal Butte's opal. Plans are to operate the mine for at least the next 5 years.
For Sale. An ore car from the Betty O’Neil Mine near Battle Mountain, Nevada. In good shape. $500.00. Contact Posey at 961-4116
For Sale. Jim Rayner in Hamilton has a 12” Rock Saw for $500 and a Fram Tom Tock Grinder Set-up with 2 diamond wheels, and a 10” trim saw with new blade, new motor on a steel stand for $800. 375-0663
SAVE USED POSTAGE STAMPS FOR CANCER RESEARCH!
GIVE A HOOT - DON"T POLLUTE! KEEP MONTANA GREEN
