ALMANDINE GARNET IN GRAPHITE from the Red Embers Mine, Erving, Franklin County, Massachusetts

Write By: tmmadmin Published In: Classic Mineral Localities Created Date: 2016-09-01 Hits: 3708 Comment: 0

Many new mineral finds make their premiere appearance at one of the many mineral shows in Tucson, Arizona, every year in February.  But at the 2014 East Coast Mineral Show, a significant and dramatic new find of highly aesthetic specimens showed up for the first time (Polityka 2014).  It consisted of almandine garnet crystals embedded in a shiny, dark silver graphite matrix; these were collected at the Red Embers mine in Erving, Franklin County, Massachusetts.  The graphite matrix had been selectively removed from both the front and back sides to expose the garnets, allowing light to shine through them, revealing the glowing, vivid burgundy-red color of the transparent gem almandine.  These specimens caused a minor uproar and were an immediate success, judging by the buzz of the crowds blocking the aisles around the booth set up by Jay Baskin of Jay's Minerals, located in New Jersey. Throughout the building people were raving about this new material, which has an extremely high “wow factor.”  The next year at the 2015 East Coast Show, Baskin returned with a new supply of this material that he had prepared over the previous year.  Buyers again lined up to purchase specimens of this extraordinary new material, including major players such as the American Museum of Natural History, the Harvard Mineralogical and Geological Museum, Yale University, the University of Arizona, and others (Polityka 2015).


Mining at the Red Embers mine (Tiffany pit in foreground)

by Eric S. Greene
www.TreasureMountainMining.com

all photos by the author

This article first appeared in the September-October, 2016 issue of Rocks & Minerals Magazine, and is used by permission. To order copies, please visit http://www.rocksandminerals.org/


Kyle Baskin and Jason Baskin cutting rock with a diamond-bladed power saw

Many new mineral finds make their premiere appearance at one of the many mineral shows in Tucson, Arizona, every year in February.  But at the 2014 East Coast Mineral Show, a significant and dramatic new find of highly aesthetic specimens showed up for the first time (Polityka 2014).  It consisted of almandine garnet crystals embedded in a shiny, dark silver graphite matrix; these were collected at the Red Embers mine in Erving, Franklin County, Massachusetts.  The graphite matrix had been selectively removed from both the front and back sides to expose the garnets, allowing light to shine through them, revealing the glowing, vivid burgundy-red color of the transparent gem almandine.  These specimens caused a minor uproar and were an immediate success, judging by the buzz of the crowds blocking the aisles around the booth set up by Jay Baskin of Jay's Minerals, located in New Jersey. Throughout the building people were raving about this new material, which has an extremely high “wow factor.”  The next year at the 2015 East Coast Show, Baskin returned with a new supply of this material that he had prepared over the previous year.  Buyers again lined up to purchase specimens of this extraordinary new material, including major players such as the American Museum of Natural History, the Harvard Mineralogical and Geological Museum, Yale University, the University of Arizona, and others (Polityka 2015).


Unprepared specimen of almandine in graphite, 39 cm


History
My first visit to the Red Embers mine was in 1993. However, it was not called the Red Embers mine back then. It was referred to as the Sky Farm locality, and my first time there was during a Keene, New Hampshire, Mineral Club field trip led by the late Wilmer Powers. He had been visiting the locality since the mid-1940s and said that the pit was originally named for the farm where the vein is exposed (Wilmer Powers, pers. comm., 1993).  Powers had been told the locality had been prospected for gem garnets in the late 1800s by Tiffany & Co. jewelers.  In the early 2000s, the site was "rediscovered" and again worked for gem-quality garnets by Jim Garabedian and his partner, Dominic LeRoux, who renamed the claim the Two Fat Guys mine (http://www.mindat.org/loc-260584.html; accessed May 2016).


Jason Baskin holds the prepared specimen shown above before rpeparation at the East Coast Mineral Show, August 2015. Specimen is now in the collection of Yale University


In 2003, as they were closing down their operation, they invited Jason Baskin to the site to collect.  Baskin, who cuts gems as a full-time job, was excited and intrigued by the clarity and color of the garnets, which he later cut into gemstones up to 4.3 carats.  He was able to negotiate with the landowner and subsequently secured an exclusive lease to work the prospect (Jay Baskin, pers. comm., 2014).  For the next six years, he sporadically worked the mine in the thick western Massachusetts forest with his cousin Kyle Baskin, his uncle Kevin Baskin, and his friend Patrick Murphy for a few weekends in the spring and for five or six more in the autumn.  The small size of the graphite exposure and the lack of easy access precluded the use of heavy machinery, and blasting would have shattered the garnets, so they mined the site using just sledges, wedges, and a gasoline-powered diamond saw. 


Patrick Murphy preparing specimens with a sandblaster

Because the graphite is virtually impossible to remove from the garnets by normal mechanical means, Baskin began experimenting with sandblasting the specimens.  After much trial and error with glass beads, corn cobs, and walnut shells, he finally discovered a crushed (angular) plastic bead medium that was hard enough to remove the graphite without scarring the surface of the garnets.  He was delighted to discover that, where the graphite has been removed from both sides of plates studded with garnet crystals, the light shining through, created a dramatic image.  Lit from the front, they are superb mineral specimens.  But backlit, the crystals' gem quality is revealed, and they glow a riveting crimson-red.  The specimens are amazingly beautiful and exhibit an attention-grabbing presence---it is easy to see where the name "Red Embers mine" came from.


Backlit almandine garnets in graphite, with dravite. Specimen is 14 cm, largest crystal 17 mm. www.TreasureMountainMining.com specimen and photo

Specimen preparation took Baskin and his team an hour for an average specimen, and up to twenty hours to prepare a large piece; the process is both painstaking and time consuming.  Most specimens include multiple garnets, though some have large single crystals.  It took nearly five years to prepare a forty-flat supply of these specimens to bring to the East Coast Show in 2014.  An additional forty flats were prepared for the 2015 show (Polityka 2015). The largest crystal found to date is 28 mm in diameter, and the largest specimen is 40 x 30 cm. It is studded with more than one hundred garnets, with individual crystals up to the size of a dime (Jay Baskin, pers. comm., 2015).


Backlit almandine crystals in graphite, with dravite. Specimen is 18.5 cm, largest almandine crystal 16 mm. www.TreasureMountainMining.com specimen and photo

The garnets are found in a vein of massive graphite that varies in thickness from 1 foot wide to nearly 6 feet wide and is adjacent to beds of mica schist.  The garnets form irregularly in layers in the graphite and are especially large and prolific in areas where the graphite has been most heavily folded.  On some specimens, dark, needle-like crystals of dravite to 2 cm are present, according to research performed at Yale University. 


Backlit almandine garnets in graphite, with dravite. Specimen is 14.5 cm, largest crystal 12 mm. www.TreasureMountainMining.com specimen and photo

The garnets have been analyzed by Stone Group Labs using Raman spectroscopic analysis on twenty-eight cut samples (Williams and Williams 2014).  The results showed that the garnets are predominantly almandine, with some areas containing spessartine and minor pyrope.  Chemical analysis by energy-dispersive X-ray fluorescence (EDXRF) spectroscopy showed a high iron content, which is consistent with almandine.  There was also some manganese and a small amount of magnesium reported.  Inclusions of apatite, along with dark-colored mica (probably biotite) were also identified.


A gem garnet after sandblasting, showing parallel striations on each face of the 19-mm crystal. Jason Baskin specimen

Most garnets, including those at Red Embers, form at convergent plate boundaries, where two tectonic plates collide, causing regional metamorphism.  The resulting heat and pressure break chemical bonds and cause minerals to recrystallize into new minerals, including almandine. The garnets start out as tiny grains and grow slowly over time, and their composition may change as the metamorphosis continues (http://geology.com/minerals/garnet.shtml; accessed May 2016), depending on the composition of the precursor rocks and presence of fluids (George Robinson, personal communication, 2016).

Graphite is carbon, a native element that is most commonly formed through the metamorphism of organic material in rocks.  It starts out as decaying plant and animal matter and is transformed over time by metamorphic heat and pressure.

Besides almandine and graphite, other minerals found include euhedral colorless, milky and smoky quartz that occurs between layers of graphite; yellow apatite crystals to 5 cm; staurolite crystals; biotite; and muscovite schist, some with BB-sized garnets.



Locality map

 
GEOLOGY

The Red Embers mine is located near the western Massachusetts town of Erving, in the Erving Formation, a part of the Connecticut Valley Belt.  The Erving Formation is exposed in four major areas of the Bronson Hill anticlinorium east of the Mesozoic basins in Western Massachusetts. These rocks in these formations were deposited between the Taconic and Acadian orogenies, along the eastern edge of North America.  The Erving formation is composed of Silurian and Lower Devonian rocks, which were formed about 400 to 425 million years ago.  The formation is made up of gray, bedded, fine-grained granulite in thick beds of muscovite-biotite schist.  The Erving Formation is the highest exposed unit in the Bronson Hill Anticlinorium and is between 200 and 900 meters thick (http://mrdata.usgs.gov/geology/state/sgmc-unit=MADev%B0; accessed May 2016).

 
CURRENT STATUS
The Red Embers mine property is under lease and is closed to collecting.  The site is both posted and under video surveillance.  Prospects are good for future mining and collecting of top-quality specimens. 

 
ACKNOWLEDGMENTS

I am indebted to Jason Baskin for help in preparing this article and for his creativity in developing the new preparation techniques that make Red Embers mine specimens so beautiful.  Thanks are also extended to Steven C. Chamberlain and George Robinson for reviewing the article and making helpful suggestions.

 

REFERENCES

Polityka, J.  2014. What’s new: Springfield Show 2014. Mineralogical Record 45:693-98.

Polityka, J.  2015. What’s new: Springfield Show 2015. Mineralogical Record 46:893-900.

Williams, C., and B. Williams. 2014. Almandine from Erving, Massachusetts.  Journal of Gemology 34 (4): 286-87.

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