Falcondoite , Willemseite Locality: Loma Peguera, Bonao , Monseñor Nouel Province , Dominican Republic ( Locality at mindat.org ) Size: 7.0 x 3.8 x 0.8 cm. This attractive specimen is primarily composed of a solid mass of the rare mineral Falcondoite, a nickel-rich species. A subtle, microcrystalline druse of darker olive-colored material mixed in, is the Willemseite. Rarely seen material from the type locality. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Falcondoite
A sepiolite-group mineral found in the Dominican Republic, named for the Falconbridge mining company that worked the deposit.
Intro adapted from Wikipedia (CC BY-SA).
Falcondoite is an IMA-recognized mineral species in the silicate class, with the chemical formula Ni₄Si₆O₁₅(OH)₂·6H₂O.
It crystallizes in the orthorhombic crystal system. It is a member of the Sepiolite, Clay structural group.
Key properties: Mohs hardness 2–3; specific gravity 1.9.
IMA symbol Fcd, IMA status: approved, named in 1976.
Found in garnierite veins which cut an extensive laterite, in association with a serpentinized harzburgite massif (near Bonao, Dominican Republic).
It is found associated with Sepiolite, talc, quartz (near Bonao, Dominican Republic).
The name refers to the familiar name \Falcondo" of the company operating the mine in the Dominican Republic where the mineral was first found.