The mountains in Colorado have yielded some fine specimens.  But the finest of the beryl species come from Russia.  In the Ural Mountains the crystals are small, but of fine color; in the Altai Mountains they are very large and of a greenish blue; but in the granitic ledges of Odon Tchelon in Daouria, on the frontier of China, they are found in the greatest perfection.  They occur on the summit of the mountain in irregular veins of micaceous and white indurated clay, and are greenish-yellow, pure pale green, greenish-blue and sky-blue.  The chief matrix of the beryl all over the world is graphic granite, but it may occur in other rocks.  The light green stones of Limoges in France appear in a vein of quartz traversing granite.  At Royalston we observed them to spring seemingly from the felspar and project into smoky quartz, becoming more transparent as they advanced into the harder stone.

The beryl possesses the same crystalline form and specific gravity as the emerald, but its hardness (especially in the yellow varieties) is sometimes greater.  The only perceptible difference in the two stones is in the color.  Cleaveland thought that as the emerald and beryl had the same essential characters, they might gradually pass into each other; and Klaproth, finding the oxides of both chrome and iron in one specimen, was led to take the same view.  The crystals of true emerald are almost always small (with the exception of those found in the Wald district in Siberia), whilst those of the beryl vary from a few grains to more than a ton in weight.  The crystals of both are almost invariably regular hexahedral prisms, sometimes slightly modified.  Those of the beryl we sometimes find quite flat, as though they had been compressed by force:  then again they are acicular and of extraordinary length, considering their slender diameter.  Sometimes their lateral faces are longitudinally striated, and as deeply as the tourmaline, so that the edges of the prism are rendered indistinct.  Other crystals are curved, and some perforated in the axis like the tourmaline, so as to contain other minerals.  Sometimes they are articulated like the pillars of basalt, and separated at some distance by the intervening quartz.  These modified forms give rise to curious speculations as to their formation and origin.  If we admit the action of fire (which is improbable), then the separation may be easily explained; but if we insist that they were deposited in the wet way and by slow process, how can we account for the dislocation?  “By electricity,” whispers a friend—­“by telluric magnetism, that wonderful unexplained and mysterious force which has caused the grand geological changes of the globe, and is still at work.”