In guano

Guanine is a crystalline amorphous substance that is found in guano, fish scales, and the liver of certain mammals. Guanine is responsible for the silvery iridescence of certain fish scales. Before its discovery, guanine was scraped from fish scales and used to coat beads to produce imitation pearls. Thus it was called pearl essence or pearly white in the 1700s. Guanine obtained from fish scales is used in cosmetics, especially for eye cosmetics and nail polishes. 

From the form in which the mineral constituents exist in guano, it is a manure peculiarly fitted for application in known quantities to the immediate wants of the growing crop. 

It exists naturally, combined with potassa, soda, or lime, in a great variety of plants, especially oxatis ace-tosdla and comiculata, Rumen aceinseUa and acetosa, also in guano, in certain urinary sediments and calculi,... 

Guanidine was first obtained by Strecker in 1861 by the oxidation with hydrochloric acid and potassium chlorate of guanine (a substance found in guano and closely related to uric acid). 

The most important of the double salts of phosphoric acid with ammonium and the alkali-metals is sodium ammonium hydrogen phosphate or microcosmic salt, NaNH4HP04,4H20, a constituent of putrefying urine, and also present in guano under the name stercorite.17 It can be prepared by the interaction of secondary sodium phosphate and ammonium chloride, or that of secondary ammonium phosphate and sodium chloride. It forms colourless columnar crystals belonging... 

Uric acid is associated with urea, creatine and creatinine in urine. In the urine of mammals it occurs in small amounts, the chief nitrogen compound being urea. In birds and reptiles, however, uric acid predominates and is the precursor of the related guanine in guano. 

The above-mentioned organic acids may be expected to produce conditions in which silica of silicate minerals is dissolved, and — assuming the phosphate concentration is adequate or sufficient time has elapsed at lower concentrations — the silicate minerals become replaced by phosphate minerals. Although little is known concerning the conditions of oxidation vs. reduction encountered in guano deposits, such a mode of replacement must be attributed to the conversion of feldspar laths to variscite-metavariscite at Malpelo Island (McConnell, 1943). Indeed, the conditions may be aerobic at the surface, whereas anaerobic conditions obtain at the lower portions in contact with the country rock. 

Minerals identified in guano in contact with limestone... 

Guanine—0—151—occurs in guano, in the excrements of the lower animals, 8D 1 iu the pancreas, lungs, and liver of certain mam-... 

Uric acid (2,6,8-hydroxypurine) is formed in small amounts in man, and traces are found in blood, urine, and feces. In birds and reptiles uric acid constitutes the normal metabolic end product of nitrogen and is found in large amounts in guano. 

The method used in the Fertilisers and Feeding Stuffs Regulations (1960), for the determination of potash as perchlorate in guanos and mixed fertilisers, will give generally concordant results. It is summarised below ... 

Xanthine, O5H4N4O2, is present, alone or combined, in many animal extracts, and is one of the minor constituents in mammalian urine, and in guano. Like hypoxanthine, it is chiefly of interest in being a deamination product of an amino purine, and an obligatory intermediate product in uric acid metabolism. 

Schneider, D., and D. C. Duffy. 1988. Historical variation in guano production from the Peruvian and Benguela upwelling ecosystems. Climatic Change 13 309-316. 

---