Category: Mineral of the Month

It has been quite some time since I designated the Lake Superior Agate as the mineral of the month. In honor of the museum founder, I am featuring his 5.5 agate as the mineral of the month. He found this agate at the base of Grand Sable Dunes in 1958. He had it for many years before he gathered up the courage to cut a slice off the end. I am glad he made that decision, so that I didn’t have to. I have always wondered when he cut the agate. While preparing this month’s webpage update, I noticed for the first time the date in the article that appeared in the Oscoda County News article about Axel and his big agate. The article was published in October of 1979 and appears to showing the agate before it was cut. Since Axel left Grand Marais in around 1984 to be closer to medical facilities for his ailing wife, he must have cut the agate sometime between 1979 and 1984. If this is true, he had the agate for over 20 years before he cut off the end. If any of you remember anything more about when he cut the agate, please give me a call at 906-494-2590 or send me an email at karen @ agatelady.com.

The first photo shows the carnelian eye pocket that Axel spotted from what he claimed was 50 feet away. The next photo shows that whole side, which is the opposite side from where Axel took the slice off the end. The third photo shows the conchoidal fractures on the top of the specimen. Although you certainly can tell that it is agate, you would not have expected the banding quality that was exposed with the cut, shown in the fourth photo.

The last photo shows the agate face that resulted when Axel sliced off the end. Before it was cut, the agate weighed 5.5 pounds. Just for perspective, the cut face is 6” wide and 3” tall. The agate is also 4” deep. Over the last 10 years since opening the museum I have seen a lot of agates come off the beach. All in all, though, I still have not seen one that beats Axel’s 1958 wonder.

Amazonite, sometimes called Amazonstone, is a layered form of microcline feldspar; it was originally named after the Amazon River when similar green stones were found there. However, no deposits of Amazonite have ever been found near the Amazon River. Amazonite is a rare mineral. Originally, it was obtained from the Limen Mountains in Russia. More recently, it has been mined in the Pike’s Peak area of Colorado as well as in Madagascar, Canada, Italy, and Brazil.

Although Amazonite does exhibit a beautiful green color when polished, it is difficult to fashion into jewelry because it easily fractures. Most people believed that the blue-green color was due to copper compounds. Scientists discovered in the mid-1980s, though, that the color is caused by small quantities of lead and water.

Amazonite is a relatively soft stone, ranging from 5-6 on the Mohs scale. It has a specific gravity of around 2.56. It has a vitreous luster and can be translucent, or opaque if it contains a greater amount of impurities. It has a conchoidal fracture, but an also split between the layers. Because of the crystal structure within the mineral, it produces the schiller effect similar, but not quite as dramatic, as Labradorite.

It is thought that amazonite is a soothing stone that can improve self-confidence. It can also inspire confidence and positive attitude, and therefore can also diminish fear and anxiety.

January’s mineral of the month is native copper. This interesting specimen was recently donated to the museum by Peter Pagel, from Marquette. He acquired it from the Houghton area. It is a thick slab of native copper in matrix that is 7 inches by 6 inches.
This specimen was mined from the Keweenaw Peninsula, which is the greatest native copper ore deposit ever found on earth. The deposit formed in the Mid-continent rift zone around a billion years ago. Native Americans have been mining the ore since around 3000 B.C. The first written account of copper was provided by French missionary Claude Allouez in 1667. He recorded that Indians of the Lake Superior region mined copper nuggets in shallow depressions. It was these abandoned pits that led early American prospectors to the sites where successful mines were later established. Large scale mining operations began in 1844 and continued until the 1960s when open pit mining out west became more profitable than underground mining.

The first person to report on the commercial potential of the copper deposit was state geologist, Douglass Houghton, in 1841. The Cliff mine, which was the first copper mine establised in Michigan, began operations in 1845. Copper mining in northern Michigan boomed, and from 1845 until 1887 (when it was exceeded by Butte, Montana) Michigan was the nation’s leading producer of copper. In most years from 1850 through 1881, Michigan mined more than three-quarters of the nation’s copper, and in 1869 produced more than 95% of the country’s copper. Annual production peaked in 1916 at 266 million pounds. Most of the native copper mines shut down in 1968, after producing 11 billion pounds of copper. The White Pine Mine operated until 1995. The only mine still mining copper on a small scale is the Caladonia Mine, located 20 miles northeast of Ontonogon. The mine’s owner, Richard Whiteman, has a worth-the-stop gift shop in Ontonogon called the Gitche Gumee Landing, located at 202 Ontonagon Street, 906-884-6618, www.caledoniamine.com.

The Keeweenaw deposit occurs in an area around 110 miles long, 10 miles wide, and up to a 1,000 feet deep. Throughout this area, there are amgadaloid (basaltic pocket) deposits as well as veins with copper ranging in size from microscopic grains to very large masses of up to around 1,200,000 pounds. Float copper specimens can also be found throughout the Midwest that were scraped free and deposited by Pleistocene glaciers that scoured the Keeweenaw Peninsula during the various ice ages.

One of the most interesting facts about the Keeweenaw copper is that it occurs in a fairly pure metal form called native copper. Most of the other copper deposits in the world form as copper oxides or copper sulfides that require processing to extract the copper.

Copper is a chemical element with the symbol Cu and atomic number 29. It is used extensively as an electrical conductor, heat conductor, building material, and component of various alloys. Copper is a reddish-colored metal that has its characteristic color because of its band structure. In its liquefied state, pure copper appears somewhat greenish, a characteristic shared with gold. When liquid copper is in bright ambient light, it retains some of its pinkish luster.

Civilizations in places such as Iraq, China, Egypt, Greece, India and the Sumerian cities all have early evidence of using copper. A copper pendant was found in northern Iraq that dates to 8700 BC. During the Roman Empire, copper was principally mined on Cyprus, hence the origin of the name of the metal as Cyprium, “metal of Cyprus”, later shortened to Cuprum. High demand relative to supply has caused the price of copper to spike during the last few years.

Metaphysical Properties

It has been reported that copper is an excellent conductor that amplifies thoughts, boosts confidence, and facilitates healing. It has been used to treat arthritis as well as other inflammation and circulatory diseases.

In keeping with the latest web page effort to provide information about the Lake Superior basin, this month’s Mineral of the Month is Nepheline Syenite.

Nephelene syenite is an igneous rock that consists largely of nepheline and alkali feldspar. The rocks are mostly pale colored, grey or pink, and in general appearance they are not unlike granites, but dark green varieties are also known.

Nepheline syenites typically are formed by low degrees of partial melting in the Earth’s mantle, very often in plate tectonic subduction zones. It also forms in the magma chambers of volcanos, such as that which is found on the eastern shore of Lake Superior in the Coldwell Alkaline Complex. This geologic structure consists of a curcular plug of rock, much different than any other rock in the area. It is over 15 miles in diameter, stretching from the Little Pic River to the town of Marathon.

Syenite is a rare rock in the Earth’s crust. Nepheline syenite is even less common. It has a hardness of 6, specific gravity of 2.57, and weighs 160 pounds per cubic foot. Depending on where this rock forms, it can contain up to 12 elements. The Nepheline Syenite found in Ontario formed in the middle Proterozoic age, just over 1.1 million years ago.

Nepheline syenite has become preferred to feldspar as a source of alumina and alkalis for glass manufacture. It promotes more rapid melting at lower temperatures, thus reducing energy consumption, lengthening the life of the furnace, and improving the yield and quality of the glass that is manufactured. The material is also used in ceramic glazes and enamels and in fillers in paints, papers, plastics, and foam ruber. Its solid nature enables it to be used in the building industry to make huricane and fire-proof buildings, roofing material, and decorative stone. It is also used to make self-sealing glass containers to transport nuclear waste products. Canada was the first country (1932) to develop the use of nepheline syenite as a raw material for glass, ceramic, and filler industries.

 

Recently, the museum was able to purchase some incredible museum-quality Malachite specimens to sell in the gift shop. One is pictured below. Malachite is a copper carbonate hydroxide mineral. It forms in botryoidal, fibrous, or stalagmitic masses, usually from the weathering of copper ores.

The stone’s name derives from the Greek word, molochitis, which means “mallow-green stone.” Until around 1800, pigments from this stone were used in making green paints.

Large quantities of malachite have been mined throughout the world including the Congo (Zaire), Tsumeb, Namibia, Ural Mountains, Russia, Mexico, England, and the U.S. There is archeological evidence that it has been mined for over 3,000 years in Israel, and for even longer in Egypt.

Malachite is a soft mineral with a hardness between 3.5 and 4, and a specific gravity of between 3.6 and 4. It is fragile and should be protected from scratching and sharp blows. When cutting or polishing malachite, you should be careful to protect your skin and not breath in the small microscopic splinters. You should also be careful when washing or cleaning malachite specimens because you can easily remove protective finishes.

Malachite is the anniversary gemstone for the 13th year of marriage. Some believe its metaphysical properties help to bring harmony into one’s life. It is also thought to enhance knowledge, patience, and to ward off danger and illness.

 

This month’s featured mineral is Rain Flower Agate from Nanijing, China. For those of you who periodically check which Lake Superior agates are listed on Ebay, you have seen the listings for these “Lake Superior-Like” agates. Rain Flower agates are river washed to a smooth surface featuring translucent, rich, banding patterns. They are found near the ancient site of the Gaozuo Temple and are featured at a museum located on the site. They are so admired that they were taken by the Chinese delegation to the 24th Seoul Olympic Games to represent “Peace Lucky Stone.”

A legend says that during the Liang of Southern Dynasties (502-557), Master Monk Yunguang placed a table on top of the local terrace and expounded the texts of Buddhism. Apparently, this so moved the God that the heaven rained flowers, which later became beautiful and colorful agate stones.

Yuhashi, or rain flower agate, is a compound of quartzite, flint and agate.

This month’s mineral of the month is Labradorite, which was first discovered in the Labrador Peninsula in Canada. It is also found in Norway, Finland, and Russia. It is truly a captivating mineral that displays a colorful shiller effect when held and moved during observation. The color display is from layers of intergrowth inside the crystal. These intergrowth layers are caused by compatible chemistries at high temperature becoming incompatible at lower temperature that results in a separating and layering of the crystal components. The color effect is caused when light enters the specimen, only to be refracted back and forth by the deeper layers. The refracted light is slowed as it travels through the layers and mixes with other light rays to change and produce a different wavelength of light. The color effect depends on the thickness and orientation of the layers.

Labradorite is a member of the plagioclase series of minerals, which comprises feldspars. It contains sodium, calcium, aluminum, silicon, and oxygen. The color is gray to smoky black. It has a dull to vitreous luster. The crystals are transparent to translucent. It has a conchoidal fracture pattern, a hardness of between 6 and 6.5, and a specific gravity of between 2.70 and 2.74. The flashes of color (labradorescence) can vary between blue, violet, green and sometimes orange and yellow.

 

The mineral of the month is a Lake Superior Michipicoten agate. When a newspaper article was published in 1958 featuring the museum founder, Axel Niemi, and his 5.5-pound agate, Axel received a letter from Mrs. J. Oldenkomp. She had seen the article and asked Axel if he was interested in buying an agate that she inherited from her grandfather. Apparently, he had found the agate on Michipicoten Island, located in the northeast part of Lake Superior. As was common practice back then, he had the agate cut and polished. The lapidariest received half the agate in payment, and the Oldenkomp family kept the other half. Before cutting, the agate weighed over 8 pounds!

Axel and Mrs. Oldenkomp haggled over the price of the agate for 7 years before Axel finally purchased the specimen in 1965. The letters documenting this purchase are posted in the museum. Unfortunately, Axel cut out the price in the letter so we’ll never know how much he paid for this beauty.

This month the featured mineral is Rainbow Fluorite. Fluorite is a derivative of the Latin word “fluere” which means to flow. Because of its easy melting properties, fluorite can be used during the manufacturing of steel; although its most popular use is in making jewelry. This is because fluorite is the most colorful mineral of the world and often displays distinct banded color, such as in this month’s featured mineral specimen. Fluorite can be purple, green, yellow, brown, pink, reddish-orange, and even colorless. It is a soft stone with a glassy luster and translucent. It is second only to quartz minerals in popularity. Fluorite is found worldwide, but especially in Brazil, Canada, China, England, Germany, Italy, Mexico, Norway, Russia, Argentina, Switzerland, and the USA.

At the Tucson show in February, I purchased a flat of Rainbow Fluorite slabs. A few pieces were used in the agate window pictured on this page. This particular window was sold at the Escanaba show. More will be used to make a lamp and other products. The slabs are considerably more expensive than agate, but well worth the price.

Some say that fluorite improves self-esteem, reduces stress, stimulates the imagination, and protects against illness. Others claim it has a calming energy that facilitates order and improves balance.