PRECIOUS STONES 



345 



of semiprecious stones that have long been favorites in jewelry 

 and art work. 



There are many localities in the United States where 

 handsome agates and chalcedonies occur, and some of these 

 may hereafter be commercially developed. In the agatized 

 forest, or Chalcedony park, of Arizona, an area of many 

 square miles is strewn with logs and trunks of an ancient 

 growth of trees, now completely altered to silica, and stained 

 with the richest and most varied hues by the oxides above 

 named. Silicified wood is by no means uncommon, but it 

 rarely presents such beauty of coloring as here, where fallen 

 and broken trunks many feet in length and ranging up to as 

 much as 4 feet in diameter, with the woody structure perfectly 

 visible, are converted into agate and chalcedony of every 

 mingled shade of red, brown, and purple. When polished 

 this makes one of the most beautiful and interesting ornamen- 

 tal stones in the world, and has attracted great admiration 

 abroad as well as in this country. 



The localit}^ is in Apache county, Ariz., a few miles south 

 of the Southern Pacific railroad from Adamana station, not 

 far from the town of Holbrook. It consists of three open 

 valleys or eroded areas among a wilderness of mesas and buttes. 

 The logs, more or less shattered into pieces and fragments or 

 cylindrical cross sections, lie along these valleys by thousands, 

 having been washed out of the rather soft sandstone that for- 

 merly covered the whole region and which still remains in the 

 intervening hills and buttes. At some points the logs may be 

 seen in place in the sandstone, especially at the celebrated 

 chalcedony bridge, where a large trunk spans a gully worn 

 m the side of a small hill. Geologically these beds belong to 

 the Triassic formation, equivalent to the brown and red sand- 

 stones of New Jersey and the Connecticut valley. But the trees 

 grew at a somewhat earlier time, and were overthrown and 

 buried in the sandstone when that was laid down by an in- 

 vasion. 



Another semiprecious stone which has been developed in 

 the United States within the past decade is chr\^soprase, a 

 chalcedony of a light green color, caused by the presence of 

 oxide of nickel. This stone has been highly valued for cen- 



