On the Action of Pure Water, and of Water saturated with Carbonic Acid Gas, on the Minerals of the Mica Family

1889; Geological Society of London; Volume: 45; Issue: 1-4 Linguagem: Inglês

10.1144/gsl.jgs.1889.045.01-04.24

ISSN

2058-105X

Autores

Alexander Johnstone,

Tópico(s)

Building materials and conservation

Resumo

In papers which have been published in the ‘Transactions’ of the Royal and Geological Societies of Edinburgh, the Author has already given preliminary accounts of certain of his researches into the nature of the action of water saturated with carbonic acid gas on the following mineral and rock substances:—Orthoclase, oligoclase, labradorite, muscovite and biotite, hornblende, augite, olivine, steatite, magnetite, hæmatite, calcite, siderite, and statuary marble (crystalline limestone). In the present communication he wishes to give some details of observations noted, and results of experiments carried out, while engaged in recent investigations into the nature of the changes produced by pure distilled water, and also by water saturated with carbonic acid, on the principal members of the mica family of minerals. C lassification O f T he M icas It is convenient for all ordinary purposes to arrange the micas into two great classes. Division I. comprehends the varieties which are anhydous or practically so; Division II. includes the micas which are most distinctly hydrated . Division I. In this section the micas generally known as muscovite (including lepidolite &c.) and biotite (including phlogophite and lepidomelane &c.) are placed. They are specially characterized by the possesion of a splendent or shining lustre, and of a high degree of elasticity in their fine laminæ. Normal specimens of these of these varieties contain usually from about 1 to 1·9 per cent of water, and none belonging properly to this division have more than 2·5 per cent of that liquid in their composition. They pass, however, quite gradually, by

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