Ferro-Edenite (Barkevikite) (variety of Amphibole)
Current inventory:  0 gems
 

  
Ferro-Edenite is named for its high ferrous iron content and relation to Edenite. Edenite is named for the locality at Edenville, New York, USA, although it is not certain to occur there. Barkevikite is named for its locality at Skutesundskjær near Barkevik, in the eastern part of the Langesundsfjord, Norway.

Discovered in 1946;   IMA status: Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

NaCa₂(Fe²⁺)₅(Si₇Al)O₂₂(OH)₂

Sodium Calcium Iron Aluminum Silicate Hydroxide

Molecular Weight:

991.96 gm

Composition:

Sodium

2.32 %

Na

3.12 %

Na₂O

Calcium

8.08 %

Ca

11.31 %

CaO

Aluminum

2.72 %

Al

5.14 %

Al₂O₃

Iron

28.15 %

Fe

36.21 %

FeO

Silicon

19.82 %

Si

42.40 %

SiO₂

Hydrogen

0.20 %

H

1.82 %

H₂O

Oxygen

38.71 %

O

100.00 %

100.00 %

= TOTAL OXIDE

Classification

Mineral Classification:

Silicates (Germanates)

Strunz 8th Ed. ID:

8/F.10-100

Nickel-Strunz 10th Ed. ID:

9.DE.15

9 : SILICATES (Germanates)
D : Inosilicates
E : Inosilicates with 2-periodic double chains, Si₄O₁₁; Clinoamphiboles

Related to:

Amphibole Group. Calcic Clino-Amphibole Subgroup.

Members of Group:

Amphibole Group: Calcic Clino-Amphibole Subgroup, Mg-Fe-Mn-Li Ortho-Amphibole Subgroup, Mg-Mn-Fe-Li Clino-Amphibole Subgroup, Sodic Clino-Amphibole Subgroup

Members of Subgroup:

Calcic Clino-Amphibole Subgroup: Actinolite, Barroisite, Cannilloite, Edenite, Ferro-Actinolite, Ferro-Aluminotschermakite, Ferro-Edenite, Ferro-Ferritschermakite, Ferrobarroisite, Ferrohornblende, Ferrokaersutite, Ferropargasite, Ferrorichterite, Ferro-Tschermakite, Ferrowinchite, Fluor-Cannilloite, Fluoro-Edenite, Fluoro-potassicrichterite, Hastingsite, IMA2009-091, Kaersutite, Katophorite, Magnesiohastingsite, Magnesiohornblende, Magnesiokatophorite, Magnesiosadanagaite, Magnesiotaramite, Pargasite, Parvo-Manganotremolite, Potassic-Ferrisadanagaite, Potassicpargasite, Potassicsadanagaite, Richterite, Taramite, Tremolite, Tschermakite, Winchite

Varieties:

None

Synonyms:

Ferro-edenitic-hornblende, Silicic-ferro-edenite

Crystal Data

Crystallography:

Monoclinic - Prismatic

Crystal Habit:

Commonly as well-formed prismatic crystals; fibrous; as reaction rims on pyroxenes.

Twinning:

Simple or multiple twinning || {100}

Physical Properties

Cleavage:

Distinct/Good on {110}

Fracture:

Uneven

Tenacity:

Brittle

Moh's Hardness:

5.0 - 6.0

Density:

4.62 - 4.73 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Optical Properties

Color:

Black, dark Green

Transparency:

Semi-Transparent to Opaque

Luster:

Vitreous

Refractive Index:

1.650 - 1.730  Biaxial ( - )

Birefringence:

0.0200

Dispersion:

Weak to Strong; r > v

Pleochroism:

Distinct; X = yellow; Y = green; Z = dark green

Occurances

Geological Setting:

An early or deuteric phase replacing pyroxene in syenitic ring complexes; from medium-grade metamorphic amphibolites and gneisses; from plutonic igneous rocks.

Common Associations:

Pyroxene, Ferro-Actinolite, Monazite, Magnetite, Fluorite (Tibchi ring complex, Nigeria).

Common Impurities:

None

Type Locality:

• Ferro-Edenite: Baie-des-Moutons syenitic complex, La Tabatière, Gros-Mécatina, Basse-Côte-Nord TE, Côte-Nord, Québec, Canada.
• Barkevikite: Skutesundskjær near Barkevik, in the eastern part of the Langesundsfjord, Norway.

Year Discovered:

1946

View mineral photos:

Ferro-edenite Mineral Photos and Locations

More Information

Mindat.org (Barkevikite)
Mindat.org (Ferro-Edenite)
Webmineral.com (Ferro-Edenite)

Barkevikite is an obsolete name (discredited in 1978) for an occurance of Ferro-edenite from pegmatitie formations in the eastern part of the Langesudsfjord area of Norway. Ferro-edenite is a fairly rare member of the Calcic Clino-Amphibole Subgroup of the Amphibole Group of minerals that includes Actinolite, Ferro-edenite, Kaersutite, Pargasite, Richterite and Tremolite. The Amphibole Group is an extensive and complex group of minerals currently divided into several sub-groups. Ferro-edenite is almost identical to the more common Amphibole mineral Edenite but contains more iron than magnesium, thus the name Ferro-edenite (ferro is Latin for iron). Ferro-edenite is generally darker and more dense.

Ferro-edenite is available from the Baie-des-Moutons complex, La Tabatiμere, Quebec, Canada; the Tibchi ring complex, Nigeria; Skudesundskjær (Skutesundskjær), Barkevik (Barkevika), Langesundsfjorden, Larvik, Vestfold, Norway; Hendersons Quarry, Mt. Ngongotaha, Rotorua, Bay of Plenty, North Island, New Zealand. Ferro-edenite undoubtedly occurs at other localities but qualifying analyses appear lacking.
 

  
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