My paper: Geopolymer: Inorganic polymeric new materials, J. of Thermal Analysis, vol.37 (1991) 1633-1656 (see in the Library )
1) single crystals, page 1637: this means that the crystals obtained in diluted medium, which is always the case by the fabrication of zeolites, these crystals can been seen by naked eye. They are big. The paragraph you are referring to is dealing with “Crystalline Poly(sialate) (- Si-O-Al -)”. Crystalline geopolymers require hydrothermal conditions as stated in the paragraph “Amorphous Poly(sialate-siloxo)”, page 1638.
2) Fig. 4: X-ray diffractogram: short time reaction yields a certain amount of Zeolite A. Longer time reaction prevents the formation of Zeolite A yielding only Na-PS, hydrosodalite. This can be followed by the measure of the coefficient of absorption. Zeolite A has an open structure and exhibits a very high coefficient of absorption. On the opposite, Na-PS is densely packed with a very low coefficient of absorption, 10 time less than Zeolite A. The X-ray diffraction patterns are different. The 60 minutes X-ray pattern belongs to Na-PS, not to a weak Zeolite A.
3) Since 1979, when I was able to produce the first liquid geopolymeric binder (Na,K)-PSS type, the generic term geopolymer is dedicated to liquid binders or cements like those displayed in Table 6, page 1646. I do not use this generic term to designate the crystalline material that is obtained in the ceramic bodies. The technology associated with ceramic bodies is called L.T.G.S., which means Low Temperature Geopolymeric Setting, see page 1649. When discussing with Johan van Jaarsveld, for both of us, geopolymer meant a liquid binder or a cement. In that case, geopolymers are amorphous.