ORNAMENTAL STONES. 



RHODONITE. 



Rhodonite is a silicate of manganese, 

 of a pink, or flesh-red color. It does not 

 furnish transparent gems, but occurring 

 massive in large pieces affords material 

 for table-tops, vases, jewel-boxes, paper- 

 weights, and other large objects in which 

 such a color is desired. The stone has 

 a slight translucency, which heightens its 

 effect when polished, and it is also like 

 jade in being quite tough. The Russians 

 use it more extensively perhaps than any 

 other people, often introducing it into or- 

 namental and decorative works, and it is 

 a stone especially prized by the imperial 

 family. Its hardness is 5.5-6.5 ; its spe- 

 cific gravity 3.4-3.7. Before the blow- 

 pipe it fuses easily and becomes black. 

 It crystallizes in the triclinic system. Its 

 chemical composition when pure is, silica 

 45.9; manganese protoxide -54.1. Rhod- 

 onite occurs in a number of localities, 

 the district of Ekaterinburg, in the Urals, 

 affording that used by the Russians. 

 Here it occurs in a massive, marble-like 

 form. At Cummington, Massachusetts, 

 according to Mr. G. F. Kunz, large quan- 

 tities of a pink and red color occur which 

 have been used for ornamental objects. 

 A feature of this rhodonite is its being 

 mottled and streaked with black, which 

 causes it to blend prettily with silver. 

 Rhodonite, of the variety of fowlerite, 

 that is, containing zinc, occurs among 

 other zinc ores at Franklin, New Jersey. 

 It is sometimes used for ornamental pur- 

 poses. 



THULITE. 



Another rose-red massive stone is fur- 

 nished by the variety of zoisite, known 

 as thulite. This resembles rhodonite in 

 color somewhat, but is easily distin- 

 guished by its chemical characters, zoisite 

 being a hydrous silicate of calcium and 



aluminum. It is somewhat harder than 

 rhodonite, its hardness being 6-6.5. The 

 name thulite is from Thule, an ancient 

 town of Norway, and the occurrence of 

 thulite is confined almost exclusively to 

 that country. Its use for ornamental 

 purposes is very limited ; but it answers 

 well to supply objects of this particular 

 color. 



PRECIOUS SERPENTINE. 



This mineral resembles jade in appear- 

 ance and properties, and is suited to 

 many of the ornamental uses to which 

 the former is put. Not a little so-called 

 jade is doubtless serpentine. The hard- 

 ness of serpentine is somewhat below 

 that of jade, it being 5.5, and lower. It 

 is also lighter, its specific gravity being 

 2.50-2.56. The blowpipe and chemical 

 characters also distinguish it, serpentine 

 being practically infusible before the 

 blowpipe, and decomposed by acids, while 

 jade is more or less fusible, and not at- 

 tacked by acids. In composition serpen- 

 tine is a hydrous magnesium silicate hav- 

 ing the percentages, silica 44.1, magnesia 

 43.0, and water 12.9. Like jade it does 

 not crystallize, but occurs in massive 

 forms, which show crystalline structure. 

 One of the most pleasing properties of 

 serpentine is its luster, which is sub- 

 resinous to oily. This, coupled with the 

 translucency which characterizes most 

 precious serpentine, and the excellent 

 polish which it takes, makes the stone 

 of rich effect. 



The color of precious serpentine is pri- 

 marily some shade of green, varying 

 from yellowish green to blackish green. 

 This color may be uniform or mottled, or 

 may include spots of other minerals, such 

 as white from calcite, as in several of 

 the serpentine marbles, or cherry-red 

 from iron oxide, as in the serpentine of 



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