Malachite after azurite (w. twinned crystal)

TSNB711
Specimen
Von Karabacek, H.
Exhibit 1. Malachite after azurite (with twinned crystal); 51 mm.
Exhibit 1. Malachite after azurite (with twinned crystal); 51 mm.
Image Credit: Malcolm Southwood
Exhibit 2. Malachite after azurite (with twinned crystal); 51 mm.
Exhibit 2. Malachite after azurite (with twinned crystal); 51 mm.
Image Credit: Malcolm Southwood
Exhibit 3. Specimen label (Hans von Karabacek).
Exhibit 3. Specimen label (Hans von Karabacek).
Image Credit: Malcolm Southwood
Thumbnail by 1Thumbnail by 2Thumbnail by 3

Specimen Title

Malachite after azurite (w. twinned crystal)

Principal Mineral

Malachite

Precursor Mineral

Azurite

Size

Cabinet; 51mm

Location in the Mine

First oxidation zone

Provenance

Von Karabacek, H.

Collection

MGMH; 93573

Entry Number

Specimen; TSNB711

Description

An intergrown group of bladed crystals of azurite (to 18 mm), completely replaced by velvety dark green malachite. The two largest crystals are conjoined with an angle that is consistent with twinning on [-102] (Pete Richards, pers.comm. to M. Southwood 2016; exhibits 1 and 2). The pseudomorphs rest on a crust of massive azurite with malachite and a second generation (?) of smaller (and unaltered) prismatic azurite crystals (to 6 mm) has formed at the base of the pseudomorphs.


The specimen was number 4074 in the collection of Austrian industrialist Hans von Karabacek, part of who’s collection was purchased for Harvard University in 1935. The specimen is therefore unequivocally from the first oxidation zone. Von Karabacek’s label (Exhibit 3) indicates that he recognised the presence of twinning ("Zwilling") on this specimen.