ClassicGems.net

 

Aegirine

 

Aegirine (also known as Acmite)

 

Discovered in 1835.   IMA status: Valid (pre-IMA; Grandfathered)

 

Chemistry

 

 

Chemical Formula:

NaFe3+(Si2O6)

 

Sodium Iron Silicate

Molecular Weight:

231.00 gm

Composition:

Sodium

9.95 %

Na

13.42 %

Na2O

 

Iron

24.18 %

Fe

34.56 %

Fe2O3

 

Silicon

24.32 %

Si

52.02 %

SiO2

 

Oxygen

41.56 %

O

 

 

 

 

100.00 %

 

100.00 %

= TOTAL OXIDE

 

 

Classification

   

   

Mineral Classification:

Silicates (Germanates)

Strunz 8th Ed. ID:

8/F.01-140

Nickel-Strunz 10th Ed. ID:

9.DA.25

 

9 : SILICATES (Germanates)
D : Inosilicates
A : Inosilicates with 2-periodic single chains, Si
2O6; pyroxene family

Related to:

Pyroxene Group. Clinopyroxene Subgroup.

Members of Group:

Pyroxene Group: Canaanite, Clinopyroxene Subgroup, Orthopyroxene Subgroup

Members of Subgroup:

Clinopyroxene Subgroup: Aegirine, Augite, Clinoenstatite, Clinoferrosilite, Diopside, Essenite, Grossmanite, Hedenbergite, Jadeite, Jervisite, Johannsenite, Kanoite, Kosmochlor, Kushiroite, Namansilite, Natalyite, Petedunnite, Pigeonite, Spodumene

Varieties:

Urbanite, Vanadian Aegirine

Synonyms:

Acmite, Acnite, Aegerine, Aegerite, Aegirite, Aegyrina, Aegyrine, Aegyrite, Aemite, Agirine, Jadeite-Aegirine, Natronägirin, Soda-Aegirite

 

 

Crystal Data

   

   

Crystallography:

Monoclinic - Prismatic

Crystal Habit:

Prismatic crystals, with blunt to steep terminations, to 35 cm, striated lengthwise, can be bent or twisted. In sprays of acicular crystals, fibrous, in radial concretions.

Twinning:

Simple and lamellar twinning common.

 

 

Physical Properties

   

 

Cleavage:

Distinct; Good on {110}, Parting on {100}

Fracture:

Irregular/Uneven

Tenacity:

Brittle

Moh's Hardness:

6.0

Density:

3.50 - 3.60 (g/cm3)

Luminescence:

None

Radioactivity:

Not Radioactive

 

 

Optical Properties

   

   

Color:

Green, Dark Green, Greenish Black, Black, Reddish Brown

Transparency:

Translucent to Opaque

Luster:

Vitreous to Resinous

Refractive Index:

1.720 - 1.839  Biaxial ( - )

Birefringence:

0.037 - 0.061

Dispersion:

Moderate to Strong

Pleochroism:

X = emerald green, deep green; Y = grass-green, deep green, yellow; Z = brownish green, green, yellowish brown, yellow

 

 

Occurances

   

   

Geological Setting:

Common in alkalic igneous rocks, carbonatites, and pegmatites. From regionally metamorphosed schists, gneisses, and iron formations; in blueschist facies rocks, and from sodium metasomatism in granulites. An authigenic mineral in some shales and marls.

Common Associations:

Potassic Feldspar, Nepheline, Riebeckite, Arfvedsonite, Aenigmatite, Astrophyllite, Catapleiite, Eudialyte, Sérandite, Apophyllite

Common Impurities:

Al, Ti, V, Mn, Mg, Ca, K, Zr, Ce

Co-Type Localities:

• Rundemyr, Nedre Eiker, Buskerud, Norway
• Låven, Langesundsfjorden, Larvik, Vestfold, Norway

Year Discovered:

1835

View mineral photos:

Aegirine Mineral Photos and Locations

 

 

More Information

   

   

 

Mindat.org
Webmineral.com

 

 

Aegirine, also known as Acmite, is a member of the Pyroxene Group of minerals that includes Aegirine, Diopside, Hedenbergite, Hypersthene, Jadeite, Petedunnite and Spodumene. Aegirine is a fairly common mineral, but rarely available as a gem. Not that gems would be that rare, just that they are not particularily attractive and would only be faceted for the sake of collecting. Gems are very dark green to greenish-black, almost opaque and usually very heavily included. 

Aegirine is named after Aegir, the Teutonic (Scandanavian) god of the sea. A synonym for the mineral is Acmite, from the Greek word akme for "point" in reference to the typical pointed crystals.

Current mineral sources are Mont Saint-Hilaire, Quebec, Canada; Mt. Malosa, Zomba District, Malawi; Kongsberg, Norway; Narsarssuk, Greenland; Kola Peninsula, Russia and Magnet Cove, Arkansas, USA.

Aegirine gems for sale:

We have not photographed the Aegirine gems yet. Please check back soon.

 


I love Sarah