NATURAL HISTORY 



761 



known. Diamonds are said to be of the first water 

 when very transparent, and of the second and third 

 water as the transparency decreases. 



Diopside. A crystallized variety of pyroxene (a sili- 

 cate of lime and magnesia), of a clear, grayish green 

 color; also called mussite. 



Emerald. A precious stone of a rich green color; it 

 is the most valuable variety of beryl. See BERYL. 



Epidote. A mineral, commonly of a yellowish green 

 color, occurring granular, massive, columnar, and in 

 crystals. It is a silicate of alumina, lime, and oxide of 

 iron, or manganese. 



Essonite. Cinnamon stone. A variety of garnet. It 

 is not much used. 



Opal. See OPAL. 



Fluonte. Calcium fluoride, a mineral of many dif- 

 lors, white, yellow, purple, red, etc., often very 

 beautiful. When crystallized it is commonly in cubes 

 with perfect octahedral cleavage. Some varieties are 

 used for ornamental vessels. Also called fluorspar, or 

 simply fluor. The colored varieties are often called 

 false ruby, false emerald, false topaz, false sapphire, and 

 false amethyst. For jewelry purposes the chief value of 



>ne is the expense of cutting and mounting. 

 Flint. A massive, somewhat impure variety of 

 quartz, in color usually of a gray to brown or nearly 

 black, breaking with a conchoidal fracture and a sharp 

 edge. See QUARTZ. 



Fluorspar. Same as FLCORITE. 



Garnet. \ mineral having many varieties differing 



in color and in their constituents, but with the same 



general chemical formula. The commonest color is red; 



vitreous, or glassy; and the hardness is 



greater than* that of quartz, about half as hard as the 



IK!. 



The common crystal forms are the dodecahedron and 

 trapezohedron. Besides the ret! varieties there are also 



. green, yellow, brown, and black ones. 

 The garnet is a silicate with various bases such as 

 alumina-lime (grossularite essonite or cinnamonstone), 

 alumina-magnesia (pyrope), alumina-manganese (spes- 

 . and chromium-lime (ouyarpvite, color emerald 

 green). The transparent red varieties are used as gems, 

 The garnet was the carbuncle of the ancients. Garnet 

 is a very common mineral in gneiss and mica slate. 



The finest specimens of redgarnets come from Arizona 

 and a single caret stone is worth about two dollars, 

 variety that comes from Russia is worth about 

 half as much as the diamond. 

 Bee Bum.. 



Heliotrope or Bloodstone. A green siliceous stone 

 sprinkled with jasper, as if with blood, whence the name. 

 Ilimntitr. An important ore of iron, the sesquioxide. 

 so called because of its re<i rolor when in the form of 

 powder. It occurs in splendent rhombohedral crystals, 

 and in massive and earthy forms, the last being called 

 red ochre. It is now seldom used in jewelry. 



Hyacinth. A red variety of zircon, sometimes used 

 as a gem. It resembles closely a dark Spanish topa/. 

 and is worth a little more than the garnet. 



liliocrase. A mineral occurring in tetragonal crystals 



and also massive, of a brown to green color, rarely 



sulphur yellow or blue. It is a silicate of alumina and 



ith some iron and magnesia. It is common at 



us. It is little usedT 



Indicolite. A variety of tourmaline of an indigo-blue 

 aolor. 



lolite. A silicate of alumina, iron, and magnesia, 

 having a bright blue rolor ai.-l a vitreous or glassy 

 remarkable for its dichroism, and is also 

 'lirhroite. 

 ith. Same as HYACINTH. 



A stone commonly of a pale to dark green 

 color, but sometimes whitish. It is hard and very 

 tough, capable of a fine poh-h, and is used ( 

 mental* purposes and for implement*. r.-pecialK in 

 -outline* nnd among many primitive p. 



An opaque, impu: f quartz, of 



low. ami other dull colon, breaking with a 



\ mineral occurring in thin-bladr<l 

 r all ine. aggregates, of a sky-Hue color. It is a 

 of aluminum. It is little used for jewelry. 

 Labradorite. A kind of felspar, commonly 

 a beautiful piny of bttriab-cfmy color 



d purpose*. The finest specimens 



I abrador. 



A mineral of a fine ? 



color. u->iiallv o<- nrring in small rounded mns< 

 Iv a silicate of nlutmnn. lime, at 

 limn Sulphide. It m often mar. 



spots or veins of sulphide of iron, nnd is much valued 

 namental work. 



Moonstone. A nearly pellucid variety of felspar, 

 showing pearly or opaline reflections from within. The 

 best specimens come from Ceylon. Their value is not 

 much more than the expense of cutting. 



Nephrite. A hard, compact mineral, of a dark green 

 color, formerly worn as remedy for diseases of the kid- 

 neys. whence its name kidnrystone. 



Obsidian. A kind of glass produced by volcano. 

 usually of a black color and opaque, except in thin splinters. 



Olivine. A common name of the yellowish green 

 mineral chrysolite, especially of the variety occurring in 

 eruptive rocks. See CHRYSOLITE. 



Onyx. Chalcedony in parallel layers of different 

 shades of color. It is used for making cameos, the 

 figure being cut in one layer with the next layer as a 

 background (see CAMEO). It is stained black and used 

 to make mourning jewelry. 



Opal. A mineral consisting, like quartz, of silica, 

 but inferior to quartz in hardness and specific gravity. 

 The precious opal shows a peculiar play of colors of 

 delicate tints and it is highly esteemed as- a gem. One 

 kind, with a varied play of color in a reddish ground, is 

 called harlequin opal. The fire opal (which comes from 

 Mexico) has colors like the red and yellow of flame. 

 This is not the cheap variety commonly called " Mexican 

 opal." A spherical opal about three-eighths of an inch 

 in diameter, or an oval flat opal about half an inch long. 

 would be worth about sixty dollars. A " Mexican opal 

 of the same size would be worth about fifteen dollars. 



Pearl. A shelly concretion, usually rounded, having 

 a brilliant luster, with varying tints, formed in the 

 mantle, or between the mantle and shell, of certain 

 bivalve mollusks (especially in the pearl oysters and 

 river mussels) and sometimes in certain univalves. Its 

 substance is the same as nacre, or mother-of pearl. 

 Pearls which are round, or nearly round, and of fine 

 luster, are highly prized as jewels. They are sold by 

 carat grains, instead of carats. 



Pyrope. A variety of garnet of a poppy-red or blood- 

 red color, frequently with a tint of orange. It is used 

 ad a gem. 



Rhodonite. Manganese spar, or silicate of manganese, 

 a mineral occurring crystallized and in rose-red masses. 

 It is almost entirely used for ornamental purposes, in 

 slabs, blocks, etc. 



Rock Crystal or Mountain Crystal. Any transparent 

 crystal of quartz, particularly of limpid or OOlOness 

 quartz. A sphere of rock crystal of absolutely perfect 

 clearness, about five inches in diameter, is worth at 

 lea.-t twenty t hoiisand dollars. 



Rose Quartz. A variety of quartz which is pinkish red. 



Rubeuite. A variety of tourmaline varying in color 

 from a pale rose red, to a deep ruby, and containing 

 lithium. It is a little more valuable than the garnet. 



Ruby. A precious stone of a carmine-red color, some- 

 times verging to violet, or intermediate between carmine 

 and hyacinth red. It is a crystallized variety of corun- 

 dum. The ruby from Siam is of a dark color and is 

 ealle-1 ox-blood ruby. It has about the same value as 

 the diamond. The ruby from Hurmah. called t he pigeon - 

 Mooil ruby, is of a lighter color and several times more 

 valuable than the ox-blood ruby. A fine pigeon-blood 

 ruby of two carats would be worth upwards of six 

 thousand dollars. 



Rutilr. A mineral, usually of a reddish-brown color 

 and brilliant, metallic, adamantine luster, occurring in 

 tetragonal crystals. 



.s,i/././,ir,. A variety of native corundum or alumi- 

 num sesquioxide. A- the name of a gem the term is 

 restricted to the transparent : blue. mnk. 



yellow, and oilier col,,, of the 



blue variety are n> Liable as the diamond. 



The sapphire is next to the diamond in hardness. 



of carneUan, of a reddish-yellow or 

 lor. 



\ f on vx consisting of sard and 



white chalcedony in alternate layers. See ONYX. 



. A mineral OCi f great 



hardness and various colors, as red. nireti, blue. 



:ig the gem tjntirl ruby. 

 -entially of aluminum m.-u 



n and sometime- also chromium. 

 are worth rnthrr more 

 he li:unoi,,|. 

 . ine felspar; aventir 



1 occurring in rhombic prisms, gen- 

 I pellucid, nlso colorless. 



i'sn biui-h. <>r 1.1 



ite of ; ,lumi 



I is used as a (tern. It is but little more \ 

 the garnet, except occasionally unusunl fine sped- 



k 



than half as muc 

 A 



