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                           Mineral of the Month--October

                              Spessartine Garnet

                                              Iron Aluminum Silicate

                                      Fe3Al2Si3O12

                                               Spessartine Garnet

                                              By Karissa Hendershot

Preface
Introduction
History
Mineralogy
Location
Links
Members' Gallery
Article Contributors
Photo & Graphics Credits
Suggested Reading
Invitation to Members
Past Minerals of the Month
Spessartine20255.jpg (85911 bytes) 3163.jpg (21971 bytes)
 

With an orange glow, like the setting sun...

 

...this garnet's appeal is universal!
(Top, left): Spessartine from China
Photo by and courtesy of Stan Celestian 2006

(Top, right): Spessartine on Albite
Photo by and courtesy of IC Minerals  2006

Preface    

     This month, we are learning more about recent gemstone favorite: Spessartine Garnet.

     From gem shows to jewelry stores, and in the field, this highly prized sparkly wonder may
keep our minds reminiscent on the summer sun, or on autumn pumpkins.

     Our exploration is more on the lab characteristics and some world locales.  Let's go!

 

Introduction

     Welcome to another Mineral-of-the-Month installment! 

     Our focus this month is on a specific garnet: Spessartine Garnet.  Spessartine or
spessartite garnet is one of many gems found in the garnet family.As bright orange crystals
in nature, and as a prized gemstone of the new millennium, it has a universal appeal.  Our
author this month is Karissa Hendershot, a professional geographer, avid fossil and mineral
collector, and accomplished lapidary.

Enjoy!

 

Spessartine Garnet

By Karissa Hendershot

spessartine1.jpg (6378 bytes) (Photo source: gemstone.org)

Garnets are a common mineral found in many metamorphic rocks. It is also sometimes found in
pegmatites dikes and as grains in sedimentary deposits. The name garnet comes from the Latin
word granatus which means "like a grain" in reference to the crystal form. There are many types
of garnets as the chemistry varies widely. The name spessartine comes from the locality of
Spessart, Germany. Spessartines are often brownish or brown-red. The other types of garnets
are:
andradite, grossular
, pyrope, almandine, and uvarovite.

Chemical Formula:

Fe3Al2Si3O12

Mineral Class:

Nesosilicate

Crystal System:

Isometric

Symmetry:

4/m -3 2/m

Hardness:

6.5-7.5

Specific Gravity:

4.32

Cleavage:

None

Fracture:

Conchoidal

Color:

Red-Brown to Yellow-Brown

Streak:

White

Luster:

Vitreous, Resinous

Transparency:

Transparent/Translucent

Common Habits:

Granular

Other Properties:

 

Notable Localities:

Namibia; Nigeria ; Germany; Norway; India;

 

Uses:

Cut as a gemstone, abrasives

Associated Minerals:

Albite, quartz, schorl tourmaline, fluorapatite, muscovite

 

 

HISTORY

The fantastic found of an up to then extremely rare Garnet variety puzzled experts all over the world
some years ago. On the Kunene River, on the border between Namibia and Angola, there was the
surprising and spectacular discovery of bright orange to red Spessartine, which was originally named
after their occurrence in the German Spessart Mountains. Until the legendary mine was discovered in
Namibia, Spessartines had existed as mere collector’s items or rarities. They were hardly ever used
for jewelry because they were so rare. But the new find changed the world of jewelry gemstones.
From this time on, an exceptionally fine and brightly orange-red gemstone has completed the offered
range. The trade name "Mandarin-Garnet
was coined, and the wonderfully orange colored Fine Garnet
became world-famous almost over night. Unfortunately the mine in the remote Namibian mountains
could only be exploited for a few years. Prospecting for the gemstones in the isolated bush land
became more and more complicated and expensive It had to be expected, then, that the very upstart
among the quality gemstones would only be available in limited amounts from the stocks of few
cutters. However, another sensation was caused by discovering another occurrence of the
orange-colored treasures, this time in Nigeria. In color and brilliance they are so similar to the
Namibian stones that only experienced experts will be able to tell them apart.
(Source: gemstone.org)

 

MINERALOGY

 

The garnet group of minerals show crystals with a habit of rhombic dodecahedrons and trapezohedrons.
They are
nesosilicates with the same general formula, A3B2(SiO4)3 in which the A site is usually
occupied by divalent cations (Ca, Mg, Fe2+) and the B site by trivalent cations (Al, Fe3+, Cr). The

chemical elements in garnet include calcium, magnesium, aluminium, iron2+, iron3+, chromium,
manganese, and titanium. Garnets show no cleavage and a dodecahedral parting. Fracture is
conchoidal to uneven; some varieties are very tough and are valuable for abrasive purposes. hardness
is 6.5-7.5,
specific gravity is 3.1-4.3, lustre is vitreous to resinous
,
and they can be transparent to
opaque.
(Source: About.com)

Spessartine is one of the aluminum garnets, along with almandine and pyrope forming the
"pyralspite" group. (The calcium or "ugrandite" garnets consist of uvarovite,
grossular and andradite.)
Its ideal composition is Mn3Al2(SiO4)3, with the silica groups (SiO4) being isolated, not linked in
chains or sheets as in most silicate minerals. Almandine and pyrope have iron (Fe) and
magnesium (Mg), respectively, instead of the manganese (Mn).  (From
Wikipedia, the free
encyclopedia
)  

The formulas and names of common garnet species are:

garnetlist.gif (3507 bytes)

Some rare species of garnet are known that illustrate the wide range of substitution that the garnet
crystal structure can accommodate. They include:

garnetlist2.gif (5712 bytes)  (Source: Publication #sp14-95)

There are a number of trade and variety names for garnet, most of these names are for particular
colors of a specie. Malaya or Mandarin is a trade name for a pyrope-spessartite that varies in color
from red, through shades of orange and brownish orange to peach and pink.  Natural Spessartine
is orange in color, but iron impurities are usually present, giving it a reddish or brownish color. 
Hessonite is the variety name for a fine orange, cinnamon brown, or pinkish variety of grossularite,
while tsavorite is the trade name for fine dark green grossularite. Melanite is a black titanium
bearing variety of andradite and demantoid is a rich green variety. Rhodolite is a purplish red
pyrope-almandite solid solution garnet. Fine-quality pyrope garnets from Czechoslovakia are
often called Bohemian garnets. Almandite and almandite-pyrope solid solution garnets are the
best abrasive types, but andradite, grossularite, and pyrope also are used. All species of garnet
have been used as gemstones.. Spessartine itself is not a common garnet, and is not usually
found as transparent, gem quality material.

 

 

LOCATION

 

Some other locations not listed above include Iskardu, Pakistan; Sri Lanka; Sanyeshan,
Guangdon Province, China; Broken Hill, New South Wales, Australia; and Berilanda, Ceara,
Brazil. 

Notable localities in the United States include:
(
Source: About.com)

 

California

Some of the finest quality spessartite garnet known come from pegmatites in San Diego County.
Spessartites have been found on Gem Hill near Mesa Grande and in mines in the Rincon and
Pala Districts. The most productive area with the finest quality garnets is on the western side of
Hatfield Creek Valley near Romona. Near Indian Head Hill in San Diego County is a deposit of
fine-quality hessonite garnet, and another deposit is near Dos Cabezas.

 

Colorado

Faceting-grade spessartite garnets can be found in the gas cavities in the rhyolite flow on
Ruby Mountain near Nathrop, Chaffee County.

 

Nevada

An alluvial deposit of almandite garnet is found along Hampton Creek Canyon in White Pine
County about 3 km from the mouth of the canyon. No production history is available for the
deposit. The source of the garnet is quartz-garnet-mica-staurolite schist that forms a portion
of the walls of the canyon.

Spessartine garnets can be found at Ely and several other locations in White Pine County.
Most of the dark brown crystals are of interest only as specimen, but a few will cut very
small clear stones.

 

Pennsylvania

Leiper's quarry, Avondale, Delaware Co., Pennsylvania (mindat.org)

 

Utah

Thomas Range, Juab Co.

 

Virginia

Two mines in Amelia County account for the majority of the production of gem-quality garnet,
they are the Morefield and Rutherford. The Spessartine from these mines, primarily the
Rutherford, are etched-crystal masses and fragments, not individual perfect crystals. The pieces
range from pea size to as large as a grapefruit. In 1991, a single piece, dubbed the Rutherford Lady,
was found that weighed more than 2,800 carats. Color varies from a fantastic light pure orange,
almost yellow to shades of red-orange, red, and brownish-red, but the orange overtone always
is present.

 

3163a.jpg (22675 bytes) 1729.jpg (31900 bytes)
Spessartine garnet on Albite matrix,
Little Three Mine, Ramona, San Diego County, California
Photo by and Courtesy of Isaias Casanova
Spessartine Garnet,
Pederneira Mine, Minas Gerais, Brazil
Photo by and Courtesy of Isaias Casanova

 

1814.jpg (29076 bytes) 2725.jpg (20771 bytes)
Spessartine on Microcline,
Tongbei, Yungxiao County, Fujiang, China
Photo by and Courtesy of Isaias Casanova
Spessartine on Smoky Quartz,
Tongbei, Yungxiao County, Fujiang, China
Photo by and Courtesy of Isaias Casanova

 

2631b.jpg (36696 bytes) 2733.jpg (35130 bytes)
Spessartine with Muscovite,
Tongbei area, Yungxiao County, Fujiang, China
Photo by and Courtesy of Isaias Casanova
Spessartine with Smoky Quartz on Orthoclase,
Tongbei, Yungxiao County, Fujiang, China
Photo by and Courtesy of Isaias Casanova

 

    

Links

Spessartine Garnet, University of Delaware

Garnet Fact Sheet

Spessartine Garnet at mindat.org

Garnet, Emporia State University

Alan Guisewhite's Spessartine Garnet Page

 

Members' Gallery

Here is where DMS Members can add their Spessartine Garnet photos to share with us.

 

Until Next Time

     We hope you have enjoyed our all too short visit to Spessartine Garnet.  Please join us next month,
for another article, and we shall journey together!
     Until then, stay safe, and happy collecting. hardhat2a.gif (5709 bytes)

 

 

Article Contributors

 

wikipedia.org

www.gemstone.org

United States Geological Survey

www.mindat.org

 

 

Photo & Graphics Credits

I would like to gratefully acknowledge the generous contributions of our fellow Spessartine Garnet
enthusiasts, collectors, authors, curators, professionals, and club members who made this work
possible.  Thanks.

Isaias Casanova, IC Minerals

Stan Celestian, Glendale Community College

wikipedia.org

www.gemstone.org

United States Geological Survey

 

 


2006  All contributions to this article are covered under the copyright protection of this article
and by separate and several copyright protection(s), and are to be used for the sole purposes of
enjoying this scholarly article.  They are used gratefully with express written permission of the
authors, save for generally-accepted scholarly quotes, short in nature, deemed legal to reference
with the appropriate citation and credit.
  Reproduction of this article must be obtained by express
written permission of the author, Kenneth B. Casey, for his contributions, authoring, photos, and
graphics.  Use of all other credited materials requires permission of each contributor separately
.

Links and general contact information are included in the credits above, and throughout this article.
The advice offered herein are only suggestions; it is the reader's charge to use the information
contained herein responsibly.  DMS is not responsible for misuse or accidents caused from this
article. All opinions, theories, proofs, and views expressed within this article, and in others on this
website, do not necessarily reflect the views of the Delaware Mineralogical Society. 


Suggested Reading

 

 

karissa.jpg (2366 bytes)

About the Author:  Karissa is the current President of the Delaware Mineralogical Society.  She is also a member of the Tuscarora Lapidary Society (TLS), and is an accomplished lapidarist and collector.

She also has affiliations with other mineral and fossil clubs in the eastern United States, and encourages folks of all ages on the enjoyment of our hobby.

E-mail: kdhendershot@delminsociety.net


Invitation to Members

Members,

Want to see your name in print?  Want to co-author, contribute, or author a whole Mineral of the Month article?  Well, this the forum for you!

And Members, if you have pictures, or a story you would like to share, please feel free to offer.  We'd like to post them for our mutual enjoyment.   Of course, you get full photo and author credit, and a chance to reach other collectors, hobbyists, and scientists.  We only ask that you check your facts, give credit where it is due, keep it wholesome for our Junior Members watching, and keep on topic regarding rockhounding.

You don't even have to be experienced in making a webpage.  We can work together to publish your story.  A handwritten short story with a Polaroid will do.  If you do fancier, a text document with a digital photo will suit, as well.   Sharing is the groundwork from which we can get your story out there.

Our club's webpages can reach any person surfing the net in the world, and even on the International Space Station, if they have a mind to view our website!

We are hoping for a possible tie-in to other informative programs upon which our fellow members might want to collaborate.  Contact any officer or board member with your suggestions.

Our next MOTM will be a surprise.  For 2005-6, we are waiting for your suggestions.  What mineral do you want to know more about?

aniagate.gif (1920 bytes)

____________________________________

Most of the Mineral of the Month selections have come from most recent club fieldtrips and March Show Themes, and from inspriring world locales. thus far.  If you have a suggestion for a future Mineral of the Month, please e-mail me at: kencasey98@yahoo.com, or tell me at our next meeting.

 

 

Past Minerals of the Month
September 2006 Mineral of the Month: Native Silver
August 2006 Mineral of the Month: Kryptonite
July 2006 Mineral of the Month: Azurite
June 2006 Mineral of the Month: Pyromorphite
May 2006 Mineral of the Month: Tsavorite by Karissa Hendershot
April 2006 Mineral of the Month: Variscite
March 2006 Mineral of the Month: Petrified Wood, Part II
February 2006 Mineral of the Month: Petrified Wood, Part I
January 2006 Mineral of the Month: Strontianite by Karissa Hendershot
December Mineral of the Month: Clinozoisite
November Mineral of the Month: Bismuth
October Mineral of the Month: Wulfenite by Karissa Hendershot
September Mineral of the Month: Turquoise
August Mineral of the Month: Peridot
July Mineral of the Month: Ruby
June Mineral of the Month: Antarctic Fluorite
May Mineral of the Month: Dolomite, Part 2
April Mineral of the Month: Dolomite, Part 1
March Mineral of the Month: Calcite
February Mineral of the Month: Agate
January Mineral of the Month: Fluorite
December Mineral of the Month: Pyrite
November Mineral of the Month: Stilbite  
October Mineral of the Month: Celestite   
 

This page last updated:  February 19, 2011 10:14:49 AM

 

       

  


Next Meeting
 

April Program, Monday, April 8, 2013:

"Destruction of the Fossil Exposures in the Chesapeake Bay Area" presented by Dr. Lauck Ward

General Club Meeting:
April 8, 2013
(Monday)

We are meeting at
Greenbank Mill


Special Meetings:
 

*Show Committee Meeting, April or May, 2013

*New Home/Lapidary Committee, 2013

*Board Meeting,  April, 2013

Next Field Trips
 

Fieldtrips!

Past Fieldtrips
 

Next Show
DMS March Show
March 1-2, 2014 at DelTech Stanton

 


Our 2013 Show Theme was:
"All That Glitters is as Good as Gold!"

March Show 2013 Report

Updates!

 

 

 
Articles

 

Fossil Forum


"Dinny, the Dino"

"Belemnites are coming"

 

MOTM June also commemorates our 50th Show!

It's shiny, yellow, and is a symbol of 50 Years!Can you guess?

Past MOTM

Collecting Adventure Stories:

"Sunny Brook Crick Goethite" by Joe Dunleavy