MINERAL OF THE MONTH: Summer 2008 Marra Mamba Tiger’s Eye

The mineral of the month for the summer 2008 update is Marra Mamba Tiger’s Eye. This mineral is found in western Australia, near Mount Brockman, but is thought to have been mined out over a decade ago. It forms when silica quartz replaces crocidolite (asbestiform riebeckite). Marra Mamba tiger’s Eye is known for its quality because it also contains red jasper, yellow chert, and black magnetite. I call it the psychology rock because people see different images in its chatoyant patterns. The fibrous nature of its parallel banded structure causes light to reflect through the layers, that roughly resembles the eyes of tigers or hawks. When there is enough magnetite in a specimen, it can be magnetic.

Other locations for tiger’s eye include South Africa, India, Myanmar, Sri Lanka, China, Brazil, Namibia, and California.

Tiger’s Eye is the planetary stone for Gemini (May 21 – June 20), and the celebratory gem stone for the ninth wedding anniversary.

It is thought by some to help with health and spiritual well being. Others believe that it is a psychic protector, aids in business, and helps one to achieve clarity.

MINERAL OF THE MONTH: June 2008 Ocean Jasper

At the request of a customer, I am going to again feature Ocean Jasper as the Mineral of the Month. Ocean Jasper made an appearance on the original web page several years ago, but it deserves to come back.

Until I completed an Internet search about Ocean Jasper while preparing this web page update, I wasn’t sure exactly when I first saw Ocean Jasper. Now I realize that it was at the Denver Show in 2000. I remember that I was visiting the exhibits housed in motel rooms. As I walked down the corridor, I passed a room that had a slab of Ocean Jasper that was six foot tall! It stopped me in my tracks! Although their high prices were appropriate given that it was a brand new mineral, I thought I would be smart and check out the Ebay prices when I returned home. I was successful in purchasing some of the magnificent mineral, but I paid for it. I bought the two specimens below from a couple in Great Britain. I paid $150 for the round slab and $75 for the egg. However, they are still two of my favorite pieces of Ocean Jasper. Notice the chrysoprase band in the round specimen and the agate pockets in the pink egg-like specimen.

 

I also must correct the historical information about this mineral that I have been presenting at the museum. I was told years ago that it was discovered eight years ago by two guys who were rock-climbing on the northern coast of Madagascar. Instead, it appears that the mineral had been discovered at the early part of last century. An article appeared about the unusual mineral in 1922. Then, the mineral was basically lost to the world for over 70 years. In 1997, the Mineralogical Encyclopedia (GRUND Publisher) reproduced a picture of the mysterious jasper showing the orbicular structures. The caption for the photo said that the source of the mineral was unknown. This picture excited rockhounds, including the field explorers for Madagascar Minerals who launched an expedition to locate the source. Their first attempt failed, so they regrouped and decided to methodically search the entire northern coastline of Madagascar. They spent 45 days navigating the coast, stopping in villages to ask locals if they were familiar with the mineral. Finally, they found the 50 x 30 yard deposit in shallow water in a remote area, It could only be seen and mined during low tide. The company had to work from boats, since the isolated region is not near a town and has no road access.

It is rare for new minerals to be discovered in this well-traveled world. Usually, new materials brought to market are usually just new deposits of already known minerals. However, Ocean Jasper is an exception.

It is thought that Ocean Jasper formed as a rhyolitic igneous rock, rich in silica. As the lava cooled, the silica precipitated out of the magma, forming little spherical balls. Later, the entire formation converted to pure silica made up of a combination of microcrystaline agate and jasper, as well as macrocrystaline quartz. The small deposit contains a wide array of color including white, green, red, yellow, and pink. There are also botryoidal and druzy quartz formations throughout the matrix. The genesis of the orbs in this beautiful rock is not known. However, research is being conducted at the University of California at Berkley to try to uncover the mystery.

The mineral is also known as Orbicular Jasper and Fish Eye Jasper. Similar, but less dramatic jaspers are found elsewhere in the world including Poppy Jasper from Morgan Hill in Santa Clara County in California and Rain Forest Jasper from Australia.

The metaphysical properties of Ocean Jasper are thought to: enhance one’s joy, help you better connect in loving relationships, improve cooperation, and help you focus on the positive aspects of life.

MINERAL OF THE MONTH: May 2008 Apophylite

The mineral of the month for May 2008 is Apophylite. This specimen was acquired from a Brazilian dealer who was liquefying his entire inventory at the Tucson show a couple of years ago. He said something about wanting to go fishing. Apophyllite is in the Silicate class of minerals, which tend to be translucent and are lower in specific gravity and harder than most minerals. All silicates contain the silicate atomic structure, whose fundamental building block is the tetrahedron, in which one silicon atom is surrounded by four equally spaced oxygen atoms. Other silicates include quartz, chalcedony, opal, orthoclase feldspar, and amazonite.

Apophyllite is a hydrous calcium potassium fluorsilicate. It can either be colorless or white, gray, green, yellow, or red. It has a hardness of 4 ½ to 5, a specific gravity of 2.3, and has perfect cleavage in one direction. The crystals are tetragonal, usually cube like or tabular and square in cross section. It forms at low temperatures and is commonly found in cavities in basaltic pockets, where it is often associated with zeolites and prehnite. Although this specimen is from Brazil, Apophyllite can be found in the copper mines on the Keweenaw Peninsula among other places world-wide.

The name, Apophyllite, means “to leaf apart” in Greek. The name derived from the tendency of the crystals to peel off when specimens are heated due to the sudden loss of water molecules within the structure. Although collectors refer to this mineral is Apophyllite, it is no longer officially classified as a mineral. Originally, the group name referred to a specific mineral, but was redefined in 1978 to stand for a class of minerals of similar chemical makeup. Apophyllites are popular as with collectors due to their well-defined crystals, color, and abundance.

The metaphysical properties of Apophyllite are thought to enhance your analytical skills and enable you to act in a truthful and honest manner. It can also be used to help you evaluate your behaviors and attitudes so that you can identify and correct any shortcomings.

MINERAL OF THE MONTH: April 2008 Shadow Agate

The mineral of the month is my favorite agate: the shadow agate. This specimen was picked up off the Grand Marais beach by the museum founder, Axel Niemi. He found it in 1925 when he was just eight years old. He had it for almost 40 years when he finally sliced the agate, discovering the intricate banding. The best shadow agates in the world come from Lake Superior, Botswana Africa, and Queensland Australia.

Shadow agates exhibit an optical effect of movement across the bands. Depth is perceived from light penetrating and bouncing between alternating clear and opaque layers. When you move these agates back and forth, shadows can be seen racing across the surface. Many factors contribute to the shadow phenomenon including the regularity, contrast, distance, and depth of the bands. When the right conditions exist, light disappears into the clear chalcedony bands and is not reflected back out to the eye. When little or no light is returned to the line of sight, we interpret this as a dark region, or shadow.

MINERAL OF THE MONTH: March 2008 Lake Superior Agate

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.

MINERAL OF THE MONTH: February 2008 Amazonite

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.

MINERAL OF THE MONTH: January 2008 Native Copper


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.

MINERAL OF THE MONTH: December 2007 Nepheline Syenite

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.

 

MINERAL OF THE MONTH: Fall 2007 Malachite

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.

MINERAL OF THE MONTH: August 2007 Rain Flower Agate

 

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.