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STEPPED AG'ATE. (See Ribbon Agate.} 



STR'IPED JA'SPEB. The Band jaspis 

 of Werner. Quartz-jaspe onyx of 

 Haiiy. Called also Kibbon jasper. 

 This is a variety differing from 

 common jasper principally in the 

 arrangement of its colours, which 

 are various, and arranged in stripes, 

 veins, rays, and in curved, con- 

 centric zones. It occurs massive, 

 in whole beds. Specific gravity 

 from 2-44 to 2-55. Fracture flat 

 conchoidal. Opake. Being sus- 

 ceptible of a high polish, this variety 

 of jasper is used for ornamental 

 purposes. It is found principally 

 in the Uralian mountains of Siberia, 

 in Saxony, in Devonshire, and in 

 the neighbourhood of Edinburgh. 



STRO'BIL. } (from strolilus, Lat.) In 



STRO'BILE. ) botany, a pericarp formed 

 from an ament by the hardening of 

 the scales ; a catkin hardened and 

 enlarged into a seed-vessel; a seed- 

 vessel composed of ligneous scales. 



STEOMA'TETJS. An ichthyolite, exhi- 

 biting much analogy with Zeus or 

 Chsetodon, and met with in the 

 metalliferous schists of Mansfield, 

 Thuringia, &c. 



STRO'MBITE. A fossil strombus; a 

 petrified strombus. Strombites are 

 very rare: in the mountains of 

 Arragon, and in the Veronese, some 

 specimens beautifully preserved 

 have been discovered. 



STRO'MBUS. The name given by Lin- 

 n&us to a genus of univalve, spiral, 

 marine, shells : aperture much di- 

 lated: lip expanding and produced 

 into a groove. Lamarck has divi- 

 ded this genus into two subgenera, 

 Strombus and Pteroceras. In some 

 of the shells of this genus the spines 

 are of great length, and are arranged 

 round the circumference of the base, 

 being at first tubular, and after- 

 wards solid, according to the period 

 of growth. In Turton's Linne, 

 fifty-five species of strombi are 

 described. 



STEO'NTIA. } A mineral sometimes 



STBO'NTIAN. ) transparent and co- 

 lourless, but generally with a tinge 

 of yellow or green. Hardness = 

 5. Specific gravity from 3*4 to 

 3-9. Texture, generally fibrous; 

 sometimes it occurs crystallized in 

 slender prismatic columns of va- 

 rious lengths. Its taste is acrid 

 and alkaline ; it converts vegetable 

 blues to green. The principal use 

 of strontian is to communicate a 

 beautiful red colour. 



STEO'NTIANITE. Carbonate of stron- 

 tian. The Strontian carbonatee 

 of Haiiy ; Strontianit of "Werner ; 

 Strontiane of Jameson; Stronthi- 

 anite of Kirwan. A mineral first 

 brought to Edinburgh from the 

 lead-mines of Strontian, in Argyle- 

 shire, in the year 1787. It greatly 

 resembles carbonate of barytes, but 

 it is not poisonous. 



STBO'NTIUM. The metallic base of 

 strontia. Strontium greatly re- 

 sembles barium in its appearance, 

 although it is, indeed, a very dif- 

 ferent substance. Strontium is 

 harmless, but barium and all its 

 salts are poisonous. The salts of 

 strontium communicate to flame a 

 fine red tinge ; those of barium, a 

 yellow. 



STETJ'CTURE. (structura, Lat.) 



1. A term used, in mineralogy, 

 to denote one of the characters of 



-minerals. The structure of a min- 

 eral depends on the shape, size, 

 and arrangement of the minute 

 parts of which it is composed. It 

 is sometimes used synonymously 

 with fracture, but it is not correct 

 so to do, there existing a consider- 

 able difference between the two 

 terms. 



2. The manner of organization of 

 animals and vegetables. The man- 

 ner in which the parts of an orga- 

 nized body are arranged among 

 themselves. 



STU'FA. (stufa, It.) A jet of steam 

 issuing from a fissure of the earth. 



