This is a thick, hot syrup. These crystals grew for about two and a half weeks before we couldn't stand it any more and took them out. There is much more information you can learn about growing crystals. See also the related article on manmade quartz crystal . The recipes above were adapted from the book Crystals and Crystal Gardens you can Grow by Jean Stangl.
Some projects create crystals in minutes, others take a few days.
It is written for younger readers, but presents crystal growing to fascinate adults too. Clear directions, illustrations, and color photos make crystal growing fast and fun. Good elementary school science projects and scout activities. Third grade and up. A book for the serious crystal grower is Crystals and Crystal Growing by Alan Holden and Phylis Morrison.