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April 30, 2017 Weekly Geology Guest, Emeralds

April 29, 2017
Greetings from the Bluff Park Back Porch, way up yonder on Shades Mountain (1,109′) in Alabama:
We will start the Segment 1 with Gems.  For this week we will look at Emeralds.
File:Gachala Emerald 3526711557 849c4c7367.jpg
Beryl, Gachala_Emerald, 858 c., La Vega de San Juan mine in Gachalá, Colombia. 2009. thisisbossi. NMNH

 
NOVA, Treasures of the Earth

http://www.pbs.org/video/2365886855/

3.    NOVA, Treasures of the Earth, Power (Fossil Fuels).

http://www.pbs.org/video/2365892300/

Beryl
Beryl is a mineral composed of beryllium aluminium cyclosilicate with the chemical formula Be3Al2(SiO3)6. Well-known varieties of beryl include emerald and aquamarine. Naturally occurring, hexagonal crystals of beryl can be up to several meters in size, but terminated crystals[clarification needed] are relatively rare. Pure beryl is colorless, but it is frequently tinted by impurities; possible colors are green, blue, yellow, red(the rarest), and white.

https://en.wikipedia.org/wiki/Beryl

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Emerald
Emerald is a gemstone and a variety of the mineral beryl (Be3Al2(SiO3)6) colored green by trace amounts of chromium and sometimes vanadium.[2] Beryl has a hardness of 7.5–8 on the Mohs scale.[2] Most emeralds are highly included,[3] so their toughness (resistance to breakage) is classified as generally poor. Emerald is a cyclosilicate.
https://en.wikipedia.org/wiki/Emerald

“Emeralds are gem-quality specimens of the beryl mineral family with a rich, distinctly green color. They are found in igneous, metamorphic, and sedimentary rocks in a small number of locations worldwide.”  Geology.com
Colombian emeralds
Emeralds from Colombia: Emeralds in a calcite and shale matrix from the Coscuez Mine, Muzo, Colombia. The well-formed crystal with an attractive green color is about 1.1 centimeters tall. Specimen and photo by Arkenstone / www.iRocks.com.
Russia emeralds
Emeralds from Russia: Photograph of emerald crystals in mica schist from the Malyshevskoye Mine, Sverdlovsk Region, Southern Ural, Russia. The large crystal is about 21 millimeters in length. Photograph © iStockphoto and Epitavi.
Crabtree Emerald Mine Pegmatite
“Emerald from North Carolina: A specimen of the Crabtree Pegmatite of western North Carolina. This granitic pegmatite filled a two-meter-wide fracture which contained emerald along the walls of the fracture and yellow beryl in the center. It was mined for emeralds by Tiffany and Company and a series of property owners between 1894 and the 1990s. Many fine clear emeralds were produced, but most of the emerald-bearing rock was sold as “emerald matrix” for slabbing and cabochon cutting. The cabochons displayed emerald and tourmaline prisms in a white matrix of quartz and feldspar. This specimen is about 7 x 7 x 7 centimeters in size and contains numerous small emerald crystals that are up to several millimeters in length and associated with schorl.”  Geology.com
>    Search:  NOVA, Treasures of the Earth, corundum, ruby.
References include:

–    Wikipedia
–    PBS, NOVA > Treasures of the Earth.
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Editors Note:  It is the intent of this site to keep this discussion as simple as possible, so as to educate the interested general public and not to discuss with the geology crowd the latest geologic theories and nuances.  Thanks, R
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“No copyright infringement intended.
The rights belong to their respective owners”

Copyright Disclaimer: Under Section 107 of the Copyright Act 1976, allowance is made for “fair use” for purposes such as criticism, comment, news reporting, teaching, scholarship, and research. Fair use is a use permitted by copyright statute that might otherwise be infringing. Non-profit, educational or personal use tips the balance in favor of fair use.

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Author’s Request:  If you see any pictures that you know the source and photographer, let me know immediately.  Thanks!  R

Images have been searched by TinEye Reverse Image Search.  http://tineye.com/
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Next week I will have a look at opals.
 
Enjoy the adventure!
 
Thanks,
R
1. Beryl, Emerald in quartz and pegmatite matrix. 2006. Madereugeneandrew

1. Beryl, Emerald in quartz and pegmatite matrix. 2006. Madereugeneandrew

2. Beryl-Emerald Crystal on Pyrite. Colombia. by unknown

2. Beryl-Emerald Crystal on Pyrite. Colombia. by unknown

3. Emerald and Albite, Columbia. by unknown

3. Emerald and Albite, Columbia. by unknown

4. Beryl, Emerald crystal, Muzo Colombia. 2009. M M

4. Beryl, Emerald crystal, Muzo Colombia. 2009. M M

5. Beryl, Emerald, Emerald. Muzo Mine, Columbia. 2010. Rob Lavinsky - 5. IRocks

5. Beryl, Emerald, Emerald. Muzo Mine, Columbia. 2010. Rob Lavinsky – 5. IRocks

1. 60 C. Mughal Emerald. Marjorie Merriweather Post Broach. 1929. Museum of Fine Artx in Boston

1. 60 C. Mughal Emerald. Marjorie Merriweather Post Broach. 1929. Museum of Fine Artx in Boston

2. Beryl, Chalk Emerald, 37.82 c.. 2007. Jorfer

2. Beryl, Chalk Emerald, 37.82 c.. 2007. Jorfer

3. Emeralds. Indian Necklace, Gachala, McKay Necklace. by unknown

3. Emeralds. Indian Necklace, Gachala, McKay Necklace. by unknown

4. Beryl, Emerald. cr. travismanley

4. Beryl, Emerald. cr. travismanley

5. Beryl, MdKay Emerald Necklace, 168c. NMNH

5. Beryl, MdKay Emerald Necklace, 168c. NMNH

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