The Cochise County Rock

Monthly Newsletter of the Sunsites Gem & Mineral Club

http://sites.google.com/site/cochisecountyrock/

“Finding and Grinding Rocks in Cochise County, Arizona since 1967”

March 2010

This issue edited by Don Hammer

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The next General Meeting of the Sunsites Gem & Mineral Club is on Monday March 8 at 7 pm at the Sunsites Community Center. Our program will be a presentation on a rich gold mine in Canada owned by former member Doug Bundy with Clive Bailey (a former Club President and mining consultant) helping on the technical aspects. We will resume the best specimen contest so bring your best azurite or malachite to the March meeting. The few raffle prizes will be unique and valuable pieces so bring your wallets for a chance on a very rare specimen.

General Meeting February 8, 2010

The meeting was called to order at 7:02

Item 1: Paul welcomed new members and visitors.

Item 2: Paul called for discussion and a motion to accept the January meeting minutes as published. The motion was made to accept the minutes without changes. The motion was seconded and approved. Thomas Rice noted that he went by Thomas, not Tom.

Item 3: Walter gave the treasurer's report which was approved without discussion.

Item 4: Don reported on the upcoming field trip to the Rosemont mines, scheduled for February 13th. More information was needed to finalize plans and details will be sent to those who have signed up for the trip. There is no limit to the number of members who would like to take advantage of

the trip, but Don or Henri need to be notified.

Item 5: Thanks to Nadine Wirshing and Walter Sigel for providing refreshments.

Following intermission and the raffle, Michael Roegner, a professional flint knapper, gave a fascinating and informative demonstration of his art. Taking a slab of Australian jasper, he knapped it down to a beautiful spear head, all the while providing interesting commentary on the

history and fine points of flint knapping, then finishing it off with a neat Clovis point.

March Field Trips

On Saturday March 13 we will go to the Commonwealth Mine for amethyst and lacy agate. Meet at 8:45 am at the vacant lot north of the Old Store in Pearce to leave at 9 am for the collecting site. The mine is under contract so this may be the last opportunity to collect there. Plan to bring heavy rock breaking and digging tools, buckets or bags, drinking water, lawn chairs, lunch and sun protection. If we have rain the trip may be postponed or canceled so check your email and the Web site and/or call Henri or Don.

On Saturday March 27 at 9 am we will go to Paul McKnight’s home in Sunizona (6355 East Duke Ranch Rd) to peruse Paul’s collection and select the rocks you want. Go south off Highway 181 on Morgan Road (0.2 miles west of Ash Creek School) for 1 ¼ miles to Paul’s long driveway. Bring your collecting bags or pails, water, lawn chairs and sun shade.

February Field Trip

Twenty members met at the 281 exit of I-10 on February 20 at 8:15 and departed at 8:30 for the Hidden Valley Ranch Core Shed about 10 miles south at Rosemont. Our guide, Jeff Cornoyer, Lead Geologist, met us there and gave us an overview of the project geology followed by showing us the various minerals in a large number of core samples from the project area. We then went a couple of miles south on 83, turned off again and dropped down to an excellent overlook of the mine site where Jeff explained the locations of the pit and various mine structures. We followed him on down to the wash and drove the wash up into the pit and he led us to some diggings with abundant malachite and a vein of nice azurite. We immediately attacked the azurite vein and broke out many large and small pieces. By noon we all had plenty and it started to sprinkle just as we got back to the vehicles. We thank Jeff Cornoyer of Rosemont Copper for giving us an excellent tour and showing us a great time.

Lapidary and Silversmith Classes

We are ready to resume our various classes. Call Larry Strout at 826-3991 if you would like to attend lapidary or wire wrapping. Larry is also teaching silver soldering, a prerequisite to silver smithing. Keith McRobert will resume teaching silver smithing. Call Don Hammer at 384-3105. Join the fun of lapidary, silversmith, and wire wrapping.

Dues are due. The Board proposed and the members approved an increase to $15 for individuals and $25 for a family. Bring your dues to the next meeting or mail your check to Sunsites Gem & Mineral Club, PO Box 87, Pearce, Arizona 85625. Unpaid members will be dropped on March 31.

Club Calendar:

March

8 General Meeting

13 Field Trip - Commonwealth Mine

27 Field Trip - Paul McKnight’s

April

1 Board Meeting

12 General Meeting

17 Field Trip

29 Board Meeting

May

10 General Meeting

15 Field Trip

27 Board Meeting

June

5 Club Picnic

Upcoming Regional Events

March 11-14 45^th Annual Deming Roundup. 9-5 daily. Free parking and admission. Contact Jerry Abbey 575-543-8915.

April 9th–11th, Treasures of the Earth Gem & Mineral Show Albuquerque, NM. Fri & Sat 10-6,

Sun. 10-5. Admission $3.00, except Friday is dollar day! All kids under age 13 are free. Over 40 dealers, Minerals & Lapidary. Creative Arts Center @ the NM State Fair Grounds. San Pedro entrance, north of Central and South of Lomas. Contact: Paul Hlava (505) 255-5478.

Azurite, the basic carbonate of copper, occurring in monoclinic crystals or masses that range from transparent to translucent and opaque. It is usually associated with malachite, which it resembles except in color. Beautiful crystals of azurite are found in the United States in Arizona and New Mexico and in France at Chessy (for which the mineral is sometimes called chessylite); they are used for ornamental purposes. Invariably blue, azurite was originally used extensively as a pigment. Notable localities for azurite are at Tsumeb, Southwest Africa, and Bisbee, Arizona.

Often found in secondary (weathered) zone of copper ore deposits. Commonly crystallized, often in large, well-formed, equidimensional, deep blue crystals and in rosette aggregates. Also in slender blue needles or even hairs. Frequently altered completely or in part to malachite. Commonly forms botryoidal growths like (and interlayered with) malachite, in crusts, stalactites, or stalagmites; also massive and earthy.

Composition - copper carbonate (69.2% CuO, 25.6% CO ₂ , 5.2% H ₂ O). Tests - copper blue color is distinctive. Fuses on charcoal, and with careful treatment will give copper bead in reducing flame. Dissolves in hydrochloric acid with effervescence. Drop of solution on platinum wire gives fine blue copper flame; green acid solution turns blue with addition of ammonia. Distinguishing characteristics - most other blue, disseminated minerals are harder. Its effervescence in acid distinguishes it from other secondary copper compounds for which it might be mistaken (relatively rare linarite is the most likely).

Occurrence - one of the very desirable mineral collectibles. Azurite forms under conditions that are identical with those of malachite, with which it is always associated. Although azurite is rarer than malachite, and apparently less stable, fine occurrences are common and much too numerous to list. Morocco has provided some good crystals, and several Arizona and Utah mines still have good crystals. Azurite and malachite stains on the rocks have served as valuable prospecting guides. Found in fine crystals in South Australia and New South Wales. Sharp brilliant crystals, the finest known and up to 6 in. (15 cm) long, were found at Tsumeb, Namibia. Clifton and Bisbee, Arizona, were noted for fine azurite crystals in their early days. Fine malachite pseudomorphs have come from Tsumeb and from Arizona.

A common habit at many mines is crystallized masses which seem to grow freely and uniformly. Azurite also grows in hollow concretionary masses with crystal-linings, a habit for which Chessy was perhaps the best example, with an occasional malachite-coated cuprite octahedron.

The mineral has been known since ancient times, and was mentioned in Pliny the Elder's Natural History under the Greek name kuanos (κυανός: "deep blue," root of English cyan) and the Latin name caeruleum. The blue of azurite is exceptionally deep and clear, and for that reason the mineral has tended to be associated since antiquity with the deep blue color of low-humidity desert and winter skies. The modern English name of the mineral reflects this association, since both azurite and azure are derived via Arabic from the Persian lazhward (لاژورد), an area known for its deposits of another deep blue stone, lapis lazuli ("stone of azure").

Azurite crystals are monoclinic, and when large enough to be seen they appear as dark blue prismatic crystals. Azurite specimens are typically massive to nodular, and are often stalactitic in form. Specimens tend to lighten in color over time due to weathering of the specimen surface into malachite. Azurite is destroyed by heat, losing carbon dioxide and water to form black, powdery copper(II) oxide. Characteristic of a carbonate, specimens effervesce upon treatment with hydrochloric acid.

Azurite was used as a blue pigment for centuries. Depending on the degree of fineness to which it was ground, and its basic content of copper carbonate, it gave a wide range of blues. It has been known as mountain blue or Armenian stone, in addition it was formerly known as Azurro Della Magna (from Italian). When mixed with oil it turns slightly green. When mixed with egg yolk it turns green-grey. It is also known by the names Blue Bice and Blue Verditer. Older examples of azurite pigment may show a more greenish tint due to weathering into malachite. Much azurite was mislabeled lapis lazuli, a term applied to many blue pigments. As chemical analysis of paintings from the Middle Ages improves, azurite is being recognized as a major source of the blues used by medieval painters. True lapis lazuli was chiefly supplied from Afghanistan during the Middle Ages while azurite was a common mineral in Europe at the time. Sizable deposits were found near Lyons, France. It was mined since the 12th century in silver mines in Saxony.

Azurite was distinguished from (the much more expensive) purified natural ultramarine blue by heating. Ultramarine withstands heat, whereas azurite turns black (copper oxide). Gentle heating of azurite produces a deep blue pigment used in Japanese painting techniques.

Azurite is used occasionally as beads and as jewelry, and also as an ornamental stone. However, its softness and tendency to lose its deep blue color as it weathers limit such uses. Heating destroys azurite easily, so all mounting of azurite specimens must be done at room temperature.

The intense color of azurite makes it a popular collector's stone. However, bright light, heat, and open air all tend to reduce the intensity of its color over time. To help preserve the deep blue color of a pristine azurite specimen, collectors should use a cool, dark, sealed storage environment similar to that of its original natural setting. (Ed note: My piece of azurite from Morenci has not changed in a drawer since 2006.)

While not a major ore of copper itself, azurite is a good surface indicator of the presence of weathered copper sulfide ores. It is usually found in association with the chemically very similar malachite, producing a striking color combination of deep blue and bright green that is strongly indicative of the presence of copper ores.

The use of azurite and malachite as copper ore indicators led indirectly to the name of the element nickel in the English language. Nickeline, a principal ore of nickel that is also known as niccolite, weathers at the surface into a green mineral (annabergite) that resembles malachite. This resemblance resulted in occasional attempts to smelt nickeline in the belief that it was copper ore, but such attempts always ended in failure due to high smelting temperatures needed to reduce nickel. In Germany this deceptive mineral came to be known as kupfernickel, literally "copper demon". The Swedish alchemist Baron Axel Fredrik Cronstedt (who had been trained by Georg Brandt, the discoverer of the nickel-like metal cobalt) realized that there was probably a new metal hiding within the kupfernickel ore, and in 1751 he succeeded in smelting kupfernickel to produce a previously unknown (except in certain meteorites) silvery white, iron-like metal. Logically, Cronstedt named his new metal after the nickel part of kupfernickel. An unintended later consequence of his choice is that both Canadian and American coins worth one-twentieth of a dollar are now named after a German term for "kobolds"—that is, they are called nickels.

Azurite is one of two basic copper(II) carbonate minerals, the other being bright green malachite. Simple copper carbonate (CuCO₃) is not known to exist in nature. In azurite, copper(II) is linked to two different anions, carbonate and hydroxide, the compound has the formula Cu₃(CO₃)₂(OH)_2. Small crystals of azurite can be obtained by rapidly stirring a few drops of copper sulfate solution into a saturated solution of sodium carbonate and allowing the solution to stand overnight.

Azurite is unstable in open air with respect to malachite, and often is pseudomorphically replaced by malachite. The weathering process effect of the replacement of some of the carbon dioxide (CO₂) units with water (H₂O). This change in the carbonate/hydroxide ratio of azurite into the 1-to-1 ratio of malachite. The conversion of azurite into malachite is attributable to the low partial pressure of carbon dioxide in air. Azurite is also incompatible with aquatic media, such as salt-water aquariums.

Club Officers for 2010

President: Paul McKnight 520-824-4054

V-President: Jack Light

Secretary: Jim Brower

Treasurer: Walter Sigel

Delegate at Large: Glen Wirshing

Hospitality Coord: Zoe Schnabel

Field Trip Coord: Henri vanden Bos

Past President: Don Hammer