O'PAH, or KINGFISII. A beautiful and pala table fish (LampriBluna) of the Mariposa family (Lampridw) and related to the John Dory (q.v.). It abounds in most northern waters, but is rare on the merican Atlantic coast. It grows to a length of four feet or more, is of oval form (see Colored Plate of (:.tms; FISHES. With TROUT), with a high dorsal fin and a powerful tail. It is brilliantly colored; the upper part of the back and sides rich green, reflecting purple and gold in different lights. the lower parts yellowish green ; round yellowish-white spots above and below the lateral line; all the tins bright ver milion. The flesh is much esteemed, This fish has many names, as 'mariposa,' 'moon-fish,' and 'king of the herrings.' Consult Hamilton, "British Fishes," in Naturalist's Library (Lon don, undated).
OPAL (Fr. opals, from Lab opoins, from Gk. dwaXXfos, opollios, opal ; connected with Skt. vpata, stone, upper millstone). A hydrous min eral silicon dioxide used as a gem. It differs from quartz by containing water, the quantity of which varies from 2 to 13 per cent, and even more. It occurs usually in pale shades of yellow, red, green, and blue, although sometimes the color is quite dark, the coloration depending on different oxides and frequently showing a bril play in the light. Opal is never found crystallized and has a eonchoidal fracture. being easily broken. Among the ancients this mineral was held precious and regarded as a lucky stone. In the East the opal is believed to make its wear er beloved of God and man so long as he trusts sincerely in its power. The finest opal is said to be among the Austrian crown jewels. It weighs seventeen ounces and is five inches long by two and a half inches in width. The principal varieties of the opal arc: (1) The precious opal; (2) lire opal: (3) girasol; (4) com mon opal. The precious opal, called also noble opal, and sometimes oriental opal. is semi transparent or translucent, usually of a bluish or yellowish-white color, yellow by transmitted light, and exhibits a beautiful play of colors, due to minute fissures which, being filled with air and moisture, reflect all prismatic colors. This variety is used principally as a gem-stone and is polished with a convex surface because its play of color is best shown in that way: but it is never cut into facets, because of its brittleness. The finest specimens are found near Kaschau, in Hungary. where they occur disseminated in the
conglomerate; also in Saxony, in Honduras. in South America, Queensland. and New South Wales in Australia, and especially near Quer4 taro, in Mexico: also at various localities in Oregon and Washington in the United States. The fire opal, which is of a hyacinth red color, with yellow and green reflections, occurs at Sima pan. in Mexico, and also in Honduras. The girasol. which is bluish-white in color with red dish reflections in a bright light, also occurs chiefly in Mexico and Central America. The common opal is semi-transparent and may he watery-white, yellow, green. red, or brown; it exhibits no play of colors. it is found in Hun gary, in various localities in Germany, in Corn wall. Pa.. Idaho Springs. Colo.. in Calaveras County. Cal., and elsewhere. Wood opal is petrified wood showing the original form and structure. Hyalite, orSItiller's glass, is a color less or whitish variety of opal, while menilite is an opaque grayish variety which is frequently found in concretionary form.
OPATA, (*Enemies,' so called by the l'ima, with whom they were anciently at war). An important tribe of Piman stock (q.v.) oc cupying the mountainous region on the head waters of the Yaqui River in Sonora and the adjacent portions of Chihuahua, Mexico. Like all the tribes of Piman affinity, their traditions indicate a northern origin. When first known to the Spaniards they were found occupyiiig set tled villages of adobe huts, and cultivating fields of corn and other vegetables. They are brave and faithful, for which reason they have been extensively employed by the Spanish and Slexi can governments as soldiers and frontier guards. They readily accepted the teachings of the mis sionaries and are now all Christianized, although still governed under the ancient forms by their village chiefs. In 1820, owing to neglect and abuse from Slexican army officers, under whom they served, their warriors revolted. Under their chiefs, Doraine and Espiritu. they defeated sev eral expeditions sent against them, making a final stand in an adobe church against a force of 2000 Slexican troops until their ammunition was exhausted, when they were obliged to surrender. The two leaders and seventeen others were shot, but the abuses of which they complained were corrected, and they have since remained quiet and loyal. They number now about 5000.