Crystal morphologies in whewellite stones: electron microscopy.

Both dried and freshly extracted samples of whewellite stones were examined by light, scanning, and transmission electron microscopy to determine the spatial distribution of the organic (matrix) and inorganic (crystal) phases. The crystalline phase was determined to occur in oriented clusters within which the crystals were stacked with their broad faces parallel. Phase contrast TEM imaging revealed gaps of the order of 100 A between all crystals, and the result of dark field TEM imaging showed that these gaps contain the amorphous phase. Thus, the indications are that the matrix is sandwiched between the crystals and may, therefore, be responsible for cohesion in these stones.