Name: Birnessite ps. Serandite, Albite with Biotite
Brand: The Arkenstone
Price: 2750 USD
Availability: InStock

Birnessite ps. Serandite, Albite with Biotite

Free shipping
Seller offers an extended return window of up to 30 days
Ships from Not specified

This is a very unusual and attractive pseudomorph of birnessite after serandite from Mont Sainte-Hilaire, from a single major find in the early 1970s by Roland Bouhelier. This is dramatic and impactful in the geometry and contrasts, as well as superb for this rare species. Several divergent sprays of charcoal gray, bladed, prismatic crystals of what was serandite, now replaced by birnessite, are set on a starkly contrasting, blocky, snow-white albite crystal. Serandite is a sodium-manganese silicate and birnessite is a sodium-calcium-manganese oxide hydrate, so this particular pseudomorph involved maintaining the sodium and manganese in the replacement process, but the silicate component was removed, oxidized, and replaced by oxygen, a little water and the addition of calcium. And amazingly in that process the original form of the serandite was preserved, but the color went from pink to charcoal! Individual crystals that make up the sprays vary in size from 1 to 3.5 cm with most averaging around 2.5 to 3 cm! The sprays are made up of a dozen or more crystals masquerade as serandite in form, but are birnessite in color and composition! Very cool! All is set off on the white albite and there is even a 2 cm, bronze-brown book of biotite set in some of the pseudomorphs! A very attractive and chemically intriguing piece! Illustrated in Collecting Pseudomorphs: The Changelings of Mineralogy (Mineralogical Record, Jan 2025) on page 77. Also illustrated in ExtraLapis #43: Pseudomorphs. Laszlo Kupi photo.