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THEOPHRASTUS ON STONES
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lar mineral should have been called anthrax, the explanation may be that spinel not only occurs in the red transparent form, to which this name was applicable without question, but also in dark or black varieties that resemble the magnetite which is often the most conspicuous component of emery. However, when anthrax is said to be similar to adamas, the reference may be, not to form or color, but rather to hardness, the special property for which adamas was noted. That would also identify this type of anthrax as spinel rather than garnet, since the hardness of spinel is close to that of emery, whereas the hardness of garnet is distinctly lower.
19. This power of resisting fire does not seem to be due to the absence of moisture, as is true of pumice and ashes. For these cannot be set on fire and burnt, because the moisture has been removed.
According to certain theories of Aristotle90 which Theophrastus appears to follow closely here, stones like anthrax are incombustible because they contain no moisture and hence lack pores of the proper size to admit fire. For much the same reason pumice and ashes are also incombustible; the difference is that they are produced from materials which originally contained moisture, whereas incombustible stones are free of moisture from the beginning.
19. pumice. In the manuscripts this word appears as κίσσηρις, except in one place in this section where it is κίτηρις. The correct form is κίσηρις, which is used by all authors except Theophrastus. The descriptions in sections 20, 21, and 22 indicate that the word sometimes denoted certain cellular or friable rock material that would not now be called pumice, but the localities that are mentioned show that ordinarily the term had the same meaning that the word pumice has today, and for that reason it has been so translated. Pliny91 shows that the corresponding Latin word pumex also had a slightly broader meaning than the modern term, though it is
»o Meteorologica, IV, 9, 387A. 81XXXVI, 154.
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