This well deserves to be investigated, both as to the polygonal figure, and as to why it does not exceed the number 6.
Rock Crystal grows ordinarily in hexagonal bars, and diamonds are found which occur with a square point and polished surfaces.

There is a species of small flat stones, piled up directly upon one another, which are all of pentagonal figure with rounded angles, and the sides a little folded inwards.

The grains of gray salt which are formed from sea water affect the figure, or at least the angle, of the cube; and in the congelations of other salts, and in that of sugar, there are found other solid angles with perfectly flat faces.

Small snowflakes almost always fall in little stars with 6 points, and sometimes in hexagons with straight sides.

And I have often observed, in water which is beginning to freeze, a kind of flat and thin foliage of ice, the middle ray of which throws out branches inclined at an angle of 60 degrees.