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Published online by Cambridge University Press: 17 January 2013
The Mineral called Analcime or Cubizite has been ranked by Haüy among those crystals which have the Cube for their primitive form; an opinion which has been adopted by all succeeding mineralogists. No distinct cleavage-planes, however, so far as I can learn, have been observed in it. Crystallographers presumed that such planes must exist, and, allowing conjecture to supply the place of observation, they considered Analcime as differing in no respect from other crystals of the same series. This opinion was first rendered doubtful by the observation, that at thicknesses of 
of an inch, it displayed a considerable action upon polarised light; but though, from the tessular form of the mineral, this fact indicated something singular in its organization, yet, owing to the great difficulty of obtaining proper specimens, I have been baffled in repeated attempts to investigate its structure.
page 187 note * Mr Phillips observes, “that there have been occasional appearances of cleavage-planes parallel to the faces of the cube.”—Mineralogy, 1823, p. 129. M. Mohs describes the cleavage as hexahedral, but imperfect. Haüy does not seem to have observed any cleavage. In the first edition of his Traité, published in 1801, he says, Les cristaux diaphanes offrent seuls quelques indices de lames paralleles aux faces du cube, tom. iii. p. 181; but in the second edition, published in 1822, he has struck out this observation. See tom. iii. p. 170. In the transparent and perfectly crystallised specimens, I cannot find any cleavages. I consider Analcime, therefore, as a mineral without cleavage; and if cleavage-planes are discovered, they will no doubt be found in the direction of the planes of no polarisation.
page 187 note † Philosophical Transactions 1818, p. 255.
page 188 note * These planes correspond with the double set of cleavage-planes which, according to Haüy, are found in Amphigene.
page 192 note * See Edinburgh Philosophical Journal, vol. i. p. 6.
page 192 note † See Edinburgh Philosophical Journal, vol. i. p, 1.; and Edinburgh Transactions, vol. ix. p. 317.