Edenite Locality: Bancroft , Bancroft District, Hastings County , Ontario , Canada ( Locality at mindat.org ) Size: 2.2 x 1.9 x 1.1 cm. Edenite (Sodium Calcium Magnesium Iron Aluminum Silicate Hydroxide) is a rare amphibole mineral (tremolite subgroup - it has an aluminum atom that is lacking in tremolite, which replaces it with an extra silicon). This is a very sharp floater crystal, with perfect form, from Canada. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Edenite
A sodium-calcium amphibole named for Edenville, New York — a double-chain silicate of the hornblende family.
Intro adapted from Wikipedia (CC BY-SA).
Edenite is an IMA-recognized mineral species in the silicate class, with the chemical formula NaCa₂Mg₅(Si₇Al)O₂₂(OH)₂.
It crystallizes in the monoclinic crystal system. It is a member of the Amphibole structural group.
Key properties: Mohs hardness 5–6; specific gravity 3.05–3.37; Vitreous luster; optically biaxial.
IMA symbol Ed, IMA status: approved, named in 1839.
Found in intermediate plutonic igneous and medium-grade metamorphic rocks, as amphibolites and marbles.
It is found associated with Titanite, mica, chondrodite (Edenville, New York, USA).
The name is derived from the locality at Edenville, New York, USA, although it is not certain to occur there.