Like beach sand, some are bigger and others are smaller but all are crystals. Each grain you see in this mosaic is a tiny crystal, several times smaller than a human hair, wherein every atom is perfectly positioned in relation to each other. Consolidated together at very high temperatures, 1700 oC (3090 oF) in this case, the grains form a dense and brittle body commonly called “ceramic”. Interestingly, many of the properties, including mechanical and optical, are strongly affected by the way the grains are bonded together. This image was obtained by scanning electron microscopy with a magnification of 3000x.