Secondary Minerals

Secondary Minerals

 

minerals formed by the chemical disintegration or displacement of minerals evolved earlier. The formation of secondary minerals is common in nature, especially in the surface zones of the earth’s crust during the processes of hypergenesis, and is also linked to changes in the physicochemical parameters of mineral formation.

The transition into secondary minerals can occur without a change in the quality of the composition of the substance— for example, the transition of chalcopyrite CuFeS2 into the secondary bornite CuFeS4. More frequently, however, transition is accompanied by the removal and exchange of substance from the surrounding medium—for instance, the formation of covellite Cu2S CuS2 through chalcopyrite, malachite Cu2[CO3](OH)2 through atacamite CuCl2 3Cu (OH)2, and kaolin through feldspar. Secondary minerals can also be formed during a purely physical change in the crystalline structure of a substance, retaining its chemical composition: cubic chalcosine changes to rhombic chalcosine, high-temperature cubic leucite changes to low-temperature rhombic leucite.

There are various forms of secondary minerals. These are powdery or other masses or pseudomorphs which retain the external form of the primary mineral while the substance is replaced by a new one.

REFERENCE

Lazarenko, E. K. Osnovy geneticheskoi mineralogii. L’vov, 1963.

G. P. BARSANOV

References in periodicals archive ?
A similar process is observed in La Atalaya, where chenevixite, tyrolite, cornwallite, olivenite and azurite were the first-formed secondary minerals, partially replaced thereafter by conichalcite.
Various secondary minerals occur in boxworks and vugs.
There are, however, many minerals in common and the more interesting of these include the secondary minerals: gaspeite, otwayite, reevesite, retgersite and zaratite.
In the old workings several secondary minerals were found, including nice malachite and allophane.
One school of thought supports a hydrothermal origin, and these secondary minerals may be related to the hydrothermal event.
Copiapite and its Al and Mg-analogs, aluminocopiapite and magnesiocopiapite, are relatively common secondary minerals in old workings of the Andrassy I, II and the Vilmos sections.
A number of fine secondary minerals can still be collected there.
(1978) Natrolite and associated secondary minerals at the Chimney Rock quarry, Bound Brook, New Jersey.
Oxidation of each set yielded a different suite of secondary minerals. Juanitaite is found in the suite designated as the copper arsenate and sulfate assemblage, which originated from the oxidation of tennantite, chalcopyrite and pyrite and consequent fluid remobilization of ions.
A variety of other primary and secondary minerals from the Pezinok antimony deposit are also very interesting for collectors.
A bulk chemical analysis of one sample of Anakeesta phyllite is given in Table 1; note the comparatively high manganese content, which accounts for the existence of spessartine garnets in the greenschist-facies rock and the presence of apjohnite among the secondary minerals.
Consequently, even where alteration of copper and cobalt sulfides begins simultaneously, and copper sulfides significantly exceed carrollite, the concentration of Co ions in solution will dominate during the deposition of Co-Cu secondary minerals until the carrollite has been exhausted.

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