Serpentinisation of tectonized Harzburgites rocks in Ophiolits of Ashin has occurred in two different phases; in the first phase this phenomenon has taken place in a static and calm condition without any mechanical deformation of the hosting Harzburgite rocks; meanwhile the ferromagnesian minerals such as olivine and pyroxene have transformed into pseudomorphous
Lhizardite and Bastite minerals .
The stone is an example of pseudomorphous
replacement (a mineral that has the crystalline form of another mineral rather than the form normally characteristic of its own composition) of crocidolite by silica.
First-rate, beautiful azurite and pseudomorphous
malachite specimens from the Milpillas mine, Sonora, Mexico, continue to be widely available, and the very reasonable prices continue to amaze.
It is pleasant to note that very fine specimens of azurite and pseudomorphous
malachite are still coming at intervals from the Milpillas mine, Sonora, Mexico (see the article in our "Mexico V" issue, November-December 2008).
This year, some busy fellows from Bougafer Minerals & Fossils (firstname.lastname@example.org) of Midelt, Morocco had a single flat in which thumbnail and miniature-size specimens of limonite pseudomorphous
after pyrite rolled and jostled about; these were found in August near Imilchil, Morocco, and are a new item from that increasingly important locality.
At a crosscut between the High Raise and Treloar veins, Sir Arthur Russell collected excellent specimens of witherite and calcite pseudomorphous
after witherite in the 1930s, and in the early 1990s Lindsay and Patricia Greenbank also took out some good specimens (about 40) at Russell's old site, which had remained untouched in the intervening decades.
By now everyone knows of the Milpillas copper mine, Cananea district, Sonora, and its world-class specimens of azurite and malachite pseudomorphous
after azurite (if somehow you don't know of it, see last year's Tucson report, the 2007 Denver report, and the article in "Mexico V," i.e.
By now you will have seen our fifth special Mexico issue (November-December 2008), and checked out the account there of the Milpillas mine, Cananea district, Sonora, Mexico--lately the talk of the mineral world for its outstanding azurite and pseudomorphous
The best pseudomorphous
malachite specimens seen so far are floater groups and matrix pieces not exceeding 7 cm, and many of the pseudocrystals are "tipped" where their terminations touched the opposite wall of the seam or vug (Jones, 2008).
But of course you've already heard that the mine produces superb azurite and malachite pseudomorphous
after azurite specimens, first seen in Denver last fall (Rob Lavinsky handling the azurites, Evan Jones the malachite pseudomorphs).