The habit of a crystal of CuSO4·5H2O can be controlled during growth under refrigeration by varying the depth of the crystal in the host solution, its crystallographic orientation duringgrowth, and the maximum size to which it is allowed to grow.

Crystals were grown in solution 30 mm deep. Those which were grown at the bottom of thesesolutions rarely produced the form1 {100}; where that form did occur, it was little more than a line face. Seeds which were set 18 mm up from the bottom yielded crystals with both {100}and {010} forms which were roughly equivalent in size. Those crystals which grew just below the surface produced {l0O} forms but no {010} forms, the opposite of crystals which developed on the bottom. {111} was usually predominant among the terminal forms, but when crystals grew to sizes greater than 0.82 cm3 in size, atthe 2 mm and 18 mm level of the solutions, {021}and {121} were almost as large as {111}. Crystals which were grown to intermediate size at all levels in the solutions developed a new form, {211}, when either the edge between (010)and (121), or that between (010) and (021) was set uppermost and parallel to the solution surface during growth. This new form generally was equal in size to the {121} form. The experimentation demonstrates that as crystals grow, the number of forms diminish in favor of those forms with minimal summation of indices.

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