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Notes on the Micro-chemical Analysis of Rock-making Minerals
Published online by Cambridge University Press: 14 March 2018
Extract
All petrologists who have worked much with the microscope must have felt the want of a system of micro-chemical analysis ar once simple and reliable. Having devoted some time to the study of micro-chemical reactions, I think it may save the time and labour of students who propose to take up the subject if I give them the result of the experience I have gained up to date.
- Type
- Research Article
- Information
- Mineralogical magazine and journal of the Mineralogical Society , Volume 10 , Issue 46 , March 1893 , pp. 79 - 122
- Copyright
- Copyright © The Mineralogical Society of Great Britain and Ireland 1893
References
page 80 note 1 Silicates, insoluble in sulphuric but soluble in hydrofluoric acid, I convert into sulphates by dissolving them in a state of fine powder in hydrofluoric acid in a platinum vessel with the aid of heat. I then add sufficient sulphurie acid to convert the bases into sulphates. On evaporation to dryness the silica is driven off in the form of fluosilicic acid and the sulphates are left behind. These can now be dissolved in water, or, in the case of barium or strontium, in hot sulphuric acid. A similar process can be used to test the purity of th0 hydrofluoric acid employed, viz. add concentrated sulphnrie acid to the HF aq. and evaporate to dryness. If the HF contains bases in any appreciable quantity they will be left behind as sulphates and may be detected under the microscope. In the case of minerals not soluble in hydrofluoric acid they must be decomposed by fusion with carbonate of soda or some other flux. See Zircon, Part III
page 81 note 1 Kristallographisch-Cherqische Tabellen, 1890.
page 81 note 2 A Treatise on Chemistry, Vol. II. The Metals. New Edn,
page 82 note 1 For the mode of ascertaining the order see my paper on Double Refraction of Minerals, Geol. Mag. 1888, p. 548. Also p. 65 of Rosenbusch's Microscopical Physiography, by Iddings.
page 83 note 1 I have occasionally given c when the vertical crystallographic axis is intontlcd,
page 84 note 1 Rdactions Microchimiques, par C. Klement et A. Renard, 1886.
page 84 note 2 Contributions to Micro.chemical Analysis, by H. Behrens. Chemical News,1891.
page 94 note 1 See Remarks, Part 3.
page 95 note 1 See Remarks, Part 3.
page 106 note 1 The bases in Part III. are arranged alphabetically with reference to their symbols; soda, for instance, being under the letter N.
page 106 note 2 By this and similar expressions it is intended that as seen in transmitted light, the crystal has a four-sided outline.
page 107 note 1 For another illustration of the same principle see Calcium (2).
page 111 note 1 Vol. II. (1), p. 203.
page 114 note 1 SnCl4 + 3H2O (in needles); SnCl4 + 5H2O (opaque acute prisms); SnCl4 + 8H2O large transparent crystals. These hydrates all crystallise in the monoclinic system.
page 118 note 1 Oxalic acid is said to crystallise in the monoclinic system, bat the prisms obtained on a glass slide have straight extinction. Double refraction very high. Major axis || to e.
page 121 note 1 When HF aq., or a fluoride, is evaporated on a glass slide the glass must be protected by a thin coat of hardened Canada balsam, as otherwise Ca, K, and other bases, would be extracted from the glass.
page 122 note 1 Behrens recommends fusion with sodium fluoride and evaporating down with sulphuric acid.