Crystals / by A.E.H. Tutton...with 120 illustrations.

  • Alfred Tutton
Date:
1911
Catalogue details

Licence: In copyright

Credit: Crystals / by A.E.H. Tutton...with 120 illustrations. Source: Wellcome Collection.

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    CHAPTER II THE MASKING OF SIMILARITY OF SYMMETRY AND CONSTANCY OF ANGLE BY DIFFERENCE OF HABIT, AND ITS INFLUENCE ON EARLY STUDIES OF CRYSTALS. Nothing is more remarkable than the great variety of geometrical shapes which the crystals of the same substance, derived from different localities or capped by low rhombohedra from the Bigrigg mine at Egremont in Cumberland, shown in Fig. 6, appear totally different from the “ dog-tooth spar '' so plenti- fully found all over the world, a specimen of which from the same mine is illustrated in Fig. 7. No mineral specimens could well appear more dissimilar than these represented on Plate III. in Figs. 6 and 7, when seen side by side in the mineral gallery of the British Museum (Natural History) at South Ken- produced under different conditions, are observed to display. One of the commonest of minerals, calcite, carbonate of lime, shows this feature admir- ably ; the beautiful large or the hexagonal prisms
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