Carnegie Museum of Natural History

One of the Four Carnegie Museums of Pittsburgh

minerals

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Roll Out the Beryl

four beryl gemstones

Beryl has many different varieties that you may be familiar with, the most recognized being: Emerald (green), Heliodor (yellow), Morganite (pink), and Aquamarine (blue or blue-green). One that you may not be familiar with is Red Beryl, a very rare variety of the species. The red is due to the trace element manganese. Red Beryl occurs in only a few places in the world and of those localities, only one of them produces crystals of the size and quality suitable for cutting gemstones, namely the Ruby Violet claims in the Wah Wah Mountains in Beaver County, Utah. For over a dozen years the Section of Minerals & Earth Sciences staff have been on the lookout for a faceted Red Beryl to put on display in the Beryl as a Gemstone exhibit in Wertz Gallery: Gems and Jewelry. But, alas, most of the Red Beryl gemstones on the market are very small because nearly all the gem rough that is produced is less than a carat in size. Faceting rough of that size usually yields gemstones of only ¼ to ½ carat, which would be too small to use in the exhibit. Occasionally we have come across gemstones of around one carat, but they were not of high enough quality for the exhibit due to poor color, poor cut, or numerous inclusions. But, as luck would have it, in March of this year I was able to acquire from Pala International a worthy, cushion cut Red Beryl gemstone with the amazing size of 2.45 carats! Together with the crystal from the same locality (acquired two years ago from Collector’s Edge) we now have a stunning rough & cut pair to represent the variety Red Beryl in the Beryl as a Gemstone exhibit.

Cut gemstone & crystal of Red Beryl from Utah

Another lesser known variety of Beryl is Goshenite, which is colorless. When Wertz Gallery opened in September of 2007 the Beryl as a Gemstone exhibit had a nice crystal of Goshenite on display from Pakistan but lacked a cut gemstone from Pakistan to go with it. In May, I acquired a beautiful 5.06 carat emerald cut Goshenite from Dudley Blauwet Gems to complement the crystal. Now every crystal on display in that exhibit has an accompanying gemstone.

Crystal & cut gemstone of Goshenite from Pakistan

Both of these new gemstones were placed on exhibit in Wertz Gallery on June 4, 2019, so stop by and see them in the Beryl as a Gemstone case!

Debra Wilson is the Collection Manager for the Section of Minerals at Carnegie Museum of Natural History. Museum employees are encouraged to blog about their unique experiences and knowledge gained from working at the museum.

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Everything Pennsylvania

On May 10th a new temporary exhibit is scheduled to be installed in Wertz Gallery: Gems and Jewelry that will feature gemstones, cabochons, polished spheres and carvings made from minerals unearthed in our own state of Pennsylvania. While we may be known as a coal producing state, there are lapidary and faceting grade minerals that are found in Pennsylvania as well. And, believe it or not, one of the polished pieces in the exhibit is a type of coal known as JET.

A carved egg made from JET, a type of LIGNITE which is a precursor to COAL.

The English noun “Jet” derives from the French word for the same material: jaiet (modern French “jais”). The adjective “jet-black,” meaning as dark a black as possible, derives from this material.

Another unusual piece in the exhibit is a carving of an elephant made from a translucent variety of ANTIGORITE known as WILLIAMSITE which is found in the State Line Chromite District in Lancaster County.

Elephant carved from WILLIAMSITE found at Lowe’s Chromite Mine in Fulton Township.

WILLIAMSITE was named in 1848 in honor of its discoverer, Lewis White Williams, a mineralogist and geologist of West Chester, Pennsylvania.

I don’t want to give away too much because I want you to come the museum to see the exhibit in person, but I will reveal two other pieces. They were personally collected at the Bingham Mine in Hamiltonban Township, Adams County, by the 1988 Carnegie Mineralogical Award winner, John Sinkankas, who also cut and polished them. The colors in these cabochons are due to the epidote and cuprite in the META-RHYOLITE, which is a silicified, or metamorphosed, RHYOLITE (an extrusive igneous rock).

META-RHYOLITE cabochons purchased from John Sinkankas in 1990.

META-RHYOLITE cabochons purchased from John Sinkankas in 1990.

Besides those pieces mentioned here, you will also see faceted gemstones of QUARTZ, AMETHYST, SMOKY QUARTZ, AQUAMARINE, and TITANITE; cabochons of MALACHITE, BLUE QUARTZ, SUNSTONE, and AMAZONITE; and polished spheres of COPPER & QUARTZ, and BLUE QUARTZ. The Cut and Polished Pennsylvania Gems and Minerals will be on exhibit in Wertz Gallery at least through the end of summer. Don’t miss it!

Debra Wilson is the Collection Manager for the Section of Minerals at Carnegie Museum of Natural History. Museum employees are encouraged to blog about their unique experiences and knowledge gained from working at the museum.

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How Do Geodes Get Their Colors?

geode

Geodes are stones with a secret–at first glance, they seem like nothing more than the grey rocks you might see on walk around your neighborhood. Then–crack!–once they’re broken open, they reveal their inner beauty: a tiny cave filled with some of the world’s most spectacular, colorful crystals.

Born out of lava

Geodes are formed when there are pockets of air within rocks. This often happens after volcanic eruptions when lava cools around air bubbles. These pockets leave space for groundwater to seep in. But the water itself doesn’t produce geodes–it brings along minerals which stay in the rock even after the water evaporates. The minerals then start to build on each other to form crystals. It can take thousands or even millions of years for these crystals to form. The larger the crystals are, the older the geode is.

So what gives them their color?

geode

The same minerals that form crystals can give them their glorious colors. Additional elements can also make their way into the mix and provide their own unique shades. Iron will give crystals a red or purple color, titanium will create blue, nickel or chromium leads to green, and manganese produces pink crystals.

While geodes can be naturally colorful some are artificially dyed. These dyed stones often have a brighter, more intense color than what appears naturally. Why do people dye geodes? Colorful geodes tend to sell well and can be a cheap way to imitate rare stones.

Come to the museum and check out the geodes of various colors on display in Hillman Hall of Minerals and Gems.

Explore nature together.  Visit Nature 360 for more activities and information.

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A Perfect Mineral for the Christmas Season

by Debra Wilson

How can you decorate a mineral for Christmas? If it’s the right mineral, all you need to do is shine a SWUV (short wave ultraviolet) light on it. Such is the case with a mineral that is known as “Christmas Ore.” Under normal light it looks like kind of a drab rock as the one in this photo does.

Christmas ore

This specimen of calcite (tan color), willemite (brown color) and franklinite (black color) is on display in Hillman Hall of Minerals and Gems in the Fluorescence & Phosphorescence exhibit and was donated by the Sterling Hill Mining Museum for this exhibit. It originated from the Sterling Hill mine in Ogdensburg, in the Franklin Mining District of New Jersey. When you shine the SWUV light on it you will see why it is called “Christmas Ore” because it glows with the colors of Christmas. The calcite glows a bright red and the willemite glows a bright green, as you can see in this photo.

christmas ore

This glowing is known as fluorescence and the Franklin Mining District is known as the fluorescent capital of the world. The Franklin and Sterling Hill ore bodies are the source of at least 350 mineral species.At present, over 80 fluorescent mineral species are known from the area. Willemite and calcite are the most common fluorescents in these ore bodies and are known as “Christmas Ore” when they occur together in the same specimen.

So, what causes the fluorescence? Fluorescence usually occurs when specific impurities known as “activators” are present within the mineral. These activators are typically cat ions of metals such as: tungsten, molybdenum, lead, boron, titanium, manganese, uranium and chromium. Rare earth elements such as europium, terbium, dysprosium, and yttrium are also known to contribute to the fluorescence phenomenon. Fluorescence can also be caused by crystal structural defects or organic impurities. Calcite (CaCO3) and willemite (Zn2SiO4) are examples of minerals that in their pure state do not fluoresce but add a little divalent manganese (Mn2+) and they will fluoresce red and green, respectively.

There are two other specimens of calcite and willemite, also from the Franklin District, in the Fluorescence & Phosphorescence exhibit, shown here under normal light and under SWUV light.

Christmas ore
christmas ore
christmas ore
Christmas ore

Come to Hillman Hall of Minerals and Gems to hear a more detailed explanation of the phenomenon of fluorescence and see all 21 specimens in the exhibit from world-wide localities that glow under the ultraviolet lights.

Debra Wilson is the Collection Manager for the Section of Minerals at Carnegie Museum of Natural History. Museum employees are encouraged to blog about their unique experiences and knowledge gained from working at the museum.

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Carnegie Museum of Natural History Blog Citation Information

Blog author: Wilson, Debra
Publication date: December 13, 2018

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