Silica appears in urinary calculi in two forms, opaline and quartz-like silica. The first one, as opaline silica, is an arrangement of small microscopical spheres whose packing shows a not so regularly ordered array as can be found in opals, formed of silica spherulites. There is also a silica deposition on organic fibers present in the calculi. There are until now only eleven observations of these kinds of silica calculi since the first description by Hammarsten et al (1953) in a man who was taking silicates because of a gastric ulcer1. The eleventh observation was published in Spain by Medina et al in 19782 (Figures 1–2). We have another unpublished one.
KeywordsUric Acid Atomic Absorption Spectrometry Calcium Silicate Renal Stone Renal Calculus
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