633 - Nontronite

ID	633
Mineral	Nontronite
Location	Divino das Laranjeiras - Minas Gerais - Brazil
Fluorescence	LW-UV: close SW-UV: close
Mindat.org	View Nontronite information at mindat.org

ID	2924
Long ID	1:1:2924:3
Formula	`Na_0.3Fe³⁺₂(Si,Al)₄O₁₀(OH)₂ · nH₂O`
IMA Status	APPROVED GRANDFATHERED
Description	Smectite Group.
Discovery Year	1827
Diapheny	Translucent,Opaque
Cleavage	{001}
Colour	Green, olive-green, yellow-green, yellow, orange, brown
Hardness (min)	1.5
Hardness (max)	2.0
About the name	Named in 1827 by Pierre Berthier for the type locality thought to be at Nontron, Dordogne, France. Actually, the type locality is at Le Manderau, Saint-Pardoux-la-Rivière, not far from Nontron. Originally named chloropal in 1822 by Dr. Johann Jakob Bernhardi and Dr. Rudolph Brandes for chlor- and opal suggesting it was a green waxy mineral somewhat resembling common opal.
Crystal System	Monoclinic
Cleavage Type	Perfect
Fracture type	Splintery,Conchoidal
Morphology	Rarely as small bladed crystals, radial or reticulated, spherulitic; commonly cryptocrystalline, claylike, massive.
shortcode_ima	Non

Nontronite