Barkevikite is definitely an name that is obsoletediscredited in 1978) for an occurance of Ferro-edenite from pegmatitie formations in the eastern part associated with the Langesudsfjord part of Norway. Ferro-edenite is a member that is fairly rare of Calcic Clino-Amphibole Subgroup regarding the Amphibole Group of minerals that includes Actinolite, Ferro-edenite, Kaersutite, Pargasite, Richterite and Tremolite. The Amphibole Group can be an extensive and group that is complex of presently split into a few sub-groups. Ferro-edenite is nearly identical to the more prevalent mineral that is amphibole 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 can be obtained 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 analyses which can be qualifying lacking.

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


Crystallography: Monoclinic – Prismatic
Crystal Habit: Commonly as well-formed prismatic crystals; fibrous; as reaction rims on pyroxenes.
Twinning: Simple or multiple twinning || {100}


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


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