Textile fabrics and their preparation for dyeing : with numerous engravings and diagrams (1906)
Hummel, J. J. (John James), d. 1902, Hasluck, Paul N. (Paul Nooncree), 1854-1931, Foster, A. R · Philadelphia : David McKay · leaf 22
. 9V *+* rough and twocut stones 4 SUPER SEVEN Growing is what crystals do, and they do it in an orderly fashion. Although there are thousands of crystal shapes in the world, they all fall into seven categories (classes) based on the symmetry, or form, of the crystal. Cubic-shaped cuprite belongs… … ^ TWO MAKES TWINS Crystals dont always growalone. Sometimes two of the samemineral will grow together, formingtwinned crystals that look like but-terfly wings. Or the two parts cangrow into each other, forming apenetration twin, such as a fairycross (at left). SPINY HABIT ► It may look like apiece…
Dyes and dyeing
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