CATALOGUE OF GEMS. 529 



Eastern coimtrios. Small crystals of g-ood color are found in the oem- 

 bearing- gravel of Expailh', France. The old lavas of Monte Somina, 

 Italy, afford small black crystals of great brilliancy. A pale blue to 

 pearl gray kind is found in the limestone near Aker, Sweden. From 

 Amity, New York, to Andover, New Jerse}^ a distance of about 

 SO miles, is a region of granular limestone and serpentine in which 

 localities of spinel abound, the crystals sometimes being tine enough to 

 afford green, black, brown, and, less commonh', red gems. The locali- 

 ties near Franklin, New Jersey, afford cr^^stals of various shades of 

 black, blue, green, and red, which will occasionally afford small gems. 

 Spinel, when pure, contains essentially 28 parts of magnesia and 72 

 parts of alumina per 100; the magnesia, however, ma}' be, and often 

 is replaced by oxides of iron, zinc, manganese, or lime. These replace- 

 ments give rise to several varieties known as automolite and gahnite, 

 zinc spinels, having a dark green to black color and a specilic gravity 

 of 1.1 to 1.9. Ceylonite, an iron magnesia spinel, usually black in 

 color, and having a density of 3.57. Chlorospinel. a magnesia, iron, 

 and alumina spinel, having a grass-green color and a specitic gravity- of 

 -3.59. Dysluite, a zinc, manganese, and iron spinel, having a yellowish 

 or graj'ish brown color with a specitic gravity of 1.55. Hercynite, an 

 iron spinel, having a specitic gravity of 8.9. 



SPODUMENE. 



HIDDENITE LITHIA EMERALD. 



Transparent spodumene affords gems varying in color from green of 

 several shades, straw yellow to yellowish white, faint reddish to ame- 

 thystine, and colorless. The mineral occurs in monoclinic crystals of 

 a prismatic habit and in cleavable masses. Its hardness is 6.5 to 7. 

 Specific gravit}', 3.13. Cleavage, prismatic and perfect. Fracture, 

 uneven; brittle. Luster, vitreous: somewhat pearly on cleavage 

 surfaces. 



Hiddenite, or lithia emerald, is a variety of spodumene varying in 

 color from a yellowish green to a deep emerald green tinged with yel- 

 low, the colors of the crystal usually })eing 3'ellow at one extremity 

 and a more or less deep green at the other. The deeper colored kinds 

 afford a gem resembling the emerald ])ut having a greater variety of 

 color because of its strong pleochroism. The mineral occurs in slender 

 prismatic crystals one-half inch to 2 inches in length, affording small 

 gems only, the largest being luidcr 3 carats in weight. Hiddenite is 

 at present known from ])ut one locality. Stony Point, Alexander 

 County, North Carolina, where it is found in metamorphic rocks, 

 generally gneiss or mica schist, in veins of kaolin. The associated 

 minerals are quartz, mica, rutilc, ber^i, and feldspar. 



Most of the gem spodumene proper comes from the province of 



