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.