References in periodicals archive ?
And Dudley had lazurite pseudomorphs after odd things, such as a sharp, bright blue, 2-cm book-shaped pseudocrystal of lazurite replacing a mica species, embedded in white marble matrix.
In general, Milpillas malachite pseudomorphs may preserve the forms either of simple bladed azurite crystals, Bisbee-style, or of more complex crystal aggregates of roughly tabular habit but showing sawtooth edges on both ends, the pseudocrystals of both types reaching 5 cm.
Jasche (1838) mentioned specimens showing pyrolusite pseudomorphs after large calcite crystals (see under Pyrolusite), as well as gray pyrolusite pseudocrystals covered by a later generation of calcite (Jaschke, 1838).
More rarely the pocket zone produced slightly rough malachite pseudomorphs after azurite to 7 cm: Evan had five miniature to small cabinet-size specimens showing the pseudocrystals.
And here's what I mean about fun facts: we are authoritatively clued in about those intriguing, earthy gray-brown pseudocrystals from Siberia which are sometimes called "achtaragdite": they are pseudomorphs of an intermediary solid solution between grossular and katoite after euhedral crystals of mayenite, an extremely rare, poorly characterized Ca-Al oxide.
And there was a flat of miniatures consisting of loose botryoidal crusts and grapy coagulations of dark to baby-blue plancheite, with malachite pseudocrystals.
The habit of the pseudocrystals varies considerably.
The pseudocrystals measure between 1 and 2 cm, exceptionally reaching 10 cm.
The malachite pseudomorphs are sharp, tabular to blocky shapes reaching 3 cm, upstanding on miniature-size matrix, the surfaces of the (completely replaced) pseudocrystals being a lush and beautiful velvety green.
Malachite shows off as rich green, botryoidal pieces with a lustrous "finish" as if highly polished; as stalactiform shapes seemingly draped in green velvet; and, of course, as big clusters of wedge-terminated pseudocrystals after azurite.
The glittering white drusy quartz crusts do not disguise the sharp forms of the former tetragonal bipyramids of apophyllite; as before, the clusters reach cabinet size, with individual pseudocrystals to 4 cm.