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Ch. 13: Olivine - Sphene

Ch. 13: Olivine - Sphene Page of 311 Ch. 13: Olivine - Sphene Text size:minus plus Restore normal size   Mail page  Print this page
272                               PRECIOUS STONES.
by its greater density and more marked dichroism. Tourmaline, which is strongly dichroic, is much less dense.
410. Axinite.
Axinite is but rarely used as a gem, although it has many properties making it suitable for such a use. In colour it varies from a pale sherry yellow to a deep brown
or almost plum colour ; the usual tint is clove brown. The lustre is vitreous, inclining to adamantine in some specimens, and the crystals are often transparent. It is doubly refracting, the indices in red light being, the greatest 1*681, and the least 1*672. It shows marked dichroism, yielding olive green and violet-blue, or cinnamon brown and violet-blue images in the dichroscope, according to the direction in which the crystal is viewed. It is pyro-
Ch. 13: Olivine - Sphene Page of 311 Ch. 13: Olivine - Sphene
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