No. 3. — Notes on the Artesian Well Sunk at Key West, Florida, 

 in 1895. By Edmund Otis Hovey. 



In 1895 an Artesian well was sunk at Key "West, Florida, to the depth 

 of 2,000 feet. Samples of the borings were taken every 25 feet from 

 the surface to the bottom, and through the kindness of Mr. Alexander 

 Agassiz a set of these samples was placed in my hands for microscopic 

 examination. The petrography of the material passed through is simple. 

 It is all an almost perfectly pure lime-rock, and is a typical oolite at the 

 surface and at 25 feet below. Beneath that depth most of the samples 

 indicate a fine or coarse, more or less loosely compacted sand-rock, 

 relieved somewhat by beds or masses of compact limestone or porous 

 rock. Small bits of oolite, or loose ovules, are present in about half of 

 the samples, indicating a shallow water origin for much of the material. 

 The most solid rock of all passed through seems to come from the depth 

 of 50 to 175 feet from the surface, inclusive. 



Perhaps the most peculiar petrographic feature is the presence in all 

 the samples except three (25, 50, 1,375 feet) of a small amount of 

 quartz. This varies from the merest trace up to a very noticeable pro- 

 portion, and is sometimes visible under a one-inch hand lens. About 

 two grams of each sample was carefully dissolved in hydrochloric acid, and 

 the residue washed and examined under a compound microscope. This 

 residue consisted mostly of a very fine-grained angular sand, havin°- 

 the lustre and fracture of quartz, and scratching glass with ease. Some 

 of the grains suggested the hexagonal outlines and pyramidal termina- 

 tion of crystals, but none was definitely made out. The particles were 

 perfectly limpid and showed no effects of abrasion. With this angular 

 sand were sometimes associated a few well rounded grains of clear 

 quartz of much larger size. Frequently the rounded grains were too 

 coarse to pass through a No. 40 mesh sieve, but this was never the case 

 with the angular material. It seems probable that the fine grained, 

 angular quartz is of secondary origin by infiltration of siliceous waters. 

 That the waters percolating through the rock strata of Florida carry 

 sdica in solution, is clearly indicated by the chalcedonized Miocene 



VOL. XXVIII. NO. 3. 



