month, we are endeavoring to learn more about: Hedenbergite.
A classic pyroxene,
Hedenbergite even occurs in our club's collecting region in Franklin,
Our exploration is more on the lab characteristics and some world locales. Let's
Our focus this
month is on: Hedenbergite. This silicate is a pyroxene, and occurs in
various colors, from green to red to black. It sometimes occurs with orange garnets
with pink calcites, giving us specimens with the red/green color combination we mentioned
Our author this month is Karissa Hendershot,
a professional geographer, avid fossil
and mineral collector, and accomplished lapidary. Enjoy!
THE MINERAL HEDENBERGITE
mineral was named after the Swedish chemist, M.A. Ludwig Hedenberg, who first
described the species.
Calcium Iron Silicate
Uses: only as a
Hedenbergite is a rock forming mineral in several metamorphic rocks, especially contact
metamorphic rocks and skarns. It is also found in some igneous rocks and ore bodies. The
mineral is a part of an important solid solution series of the pyroxene group. The series
includes the minerals diopside,
CaMgSi2 O6, and augite,
(Ca, Na)(Fe, Mg, Al)(Al, Si)2 O6.
Hedenbergite is the iron rich end member of the series. The diopside-hedenbergite series
analogous to the amphiobole, tremolite- actinolite
Color is black, greenish
black, dark green and dark brown.
Luster is vitreous to
Transparency crystals are
translucent to opaque.
Crystal System is monoclinic; 2/m
Crystal Habits include short
prismatic (with a square cross section) and accicular, rarely
fibrous crystals. Good crystals are rare, more commonly compact, granular, lamellar and
Cleavage is perfect in two
lengthwise directions at close to right angles and a basal parting
direction is sometimes seen.
Fracture is uneven to
Hardness is 5 - 6
Specific Gravity is approximately
3.2 - 3.6 (above average)
Streak is white to pale
grossular, andradite, magnetite, actinolite, galena,
common constituent of metamorphosed iron formations or other ferruginous
siliceous sediments; common in Fe-Mn skarns. In alkalic granites, syenites, and in
Fluorescence:Translucent to transparent;
light-colored varieties in dolomitic marble may
fluoresce blue or yellow.
Indicators are crystal habit,
associations, color, fracture and cleavage.
Hedenbergite is a member of the
clinopyroxenes, which crystallize in the monoclinic
system and contain calcium, iron, aluminum, sodium, or lithium. The crystals commonly
occur as radiating fibrous aggregates, with stubby, prismatic crystals of nearly square
section being rarer. They are almost opaque except when slivers viewed on the edge.
forms are often greenish-brown in color.
Although usually darker than its gemstone cousin diopside, can still be a wonderful
specimen. Its dark green to black color can be striking with the bright luster that is
some specimens. While this is not an uncommon mineral, good crystals of hedenbergite are
rare and specimens that show nice crystals, good color and luster are prized.
Occurrence and paragenesis
Found in association with minerals of
contact metamorphism and of regional metamorphism
of dolomitic limestones. Less frequently in rarer types of pegmatites.
The predominant and most abundant Hedenbergite occurrence is at Franklin, where it occurs
as dark green intergrowths with epidote and at Sterling Hill, where it occurs in several
Being Diopside's Fe-analog, Hedenbergite
found in northern New Jersey is greatly magnesian
in content, more closely resembling Diopside.
A few localities for studied
material include: in Sweden, at Nordmark, VÄarmland, and
YxsjÄo, ÄOrebro. From PrÄagraten, Tirol, Austria. At FÄurstenberg, Saxony, Germany.
From RioMarina, Elba, Italy. On Seriphos, Greece. In the USA, at Iron Hill, Gunnison Co.,
Colorado; ¯ne crystals from the Laxey mine, South Mountain, Owyhee Co., Idaho; in the
district, Pima Co., and the Westinghouse mine, Santa Cruz Co., Arizona; at Hanover, Grant
Co., New Mexico. In the Vesturhorn intrusion, southeast Iceland. Large crystals from
Hill, New South Wales,Australia. In the Obira mine, Bungo, Oita Prefecture, Japan. At
Madhya Pradesh, and Kacharwali, Nagpur district, Maharashtra, India. Fine crystals from
Skardu area, Pakistan. At Dal'negorsk, Primorskiy Kray, Russia.
The pictures show the different habits that Hedenbergite can take.
Collected at Tilcons Byram Quarry in Stanhope, New Jersey in September 2006.
Broken 1+ inch crystals surrounded by pink calcite and tiny books of Muscovite.
The Calcite can be etched out to reveal complete crystals of the Hedenbergite.
Hedenbergite, University of Delaware
Dr. Bill's Wisconsin Mineral List: Hedenbergite
Alan Guisewite's Hedenbergite Page
Mineral Description: Hedenbergite
Here is where DMS Members can add their
Hedenbergite photos to share with us.
Until Next Time
We hope you have enjoyed our all too short visit to
Hedenbergite. Please join us next month,
for another article, and we shall journey together!
Until then, stay safe, and happy collecting.
I would like to gratefully acknowledge the generous
contributions of our fellow Hedenbergite
enthusiasts, collectors, authors, curators, professionals, and club members who made this
eBay Dealers: affordableminerals, socalnevadainc, d-h-garske
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||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.