Ch. 3: Precious Gem stones in 1912

Ch. 3: Precious Gem stones in 1912 Page of 93 Ch. 3: Precious Gem stones in 1912 Text size:minus plus Restore normal size   Mail page  Print this page
GEMS AND PRECIOUS STONES.                           1035
the owners. One of these was a beautiful light, clear straw-yellow crystal which has since been cut into two perfect gems weighing 1.5 and 0.4 metric carats. These stones are very brilliant but slightly pale for the best gems. Some of the light-colored and colorless beryls would yield very brilliant gems.
Since this prospect was examined in November, 1912, a beautiful clear yellow beryl crystal weighing 70.5 grams or 352.5 metric carats, has been found. This crystal has been fractured at the ends and measures in its present form 25 by 30.5 millimeters thick and 33 to 48 millimeters long. There are three larger cracks across the crystal and other smaller flaws. The prism faces have rhombic etchings. Much of the beryl is limpid and clear and of fine gem quality. It has a light golden or rich honey-yellow color.
Good beryl is reported to have been found in the prospect of Thomas Barnes, 2 miles N. 30° W. of All Healing Springs, on a spur extending east from a mountain ridge. The prospect has been opened by four pits and open cuts in a distance of about 125 feet in a N. 15° W. direction across the ridge. The deepest pit was about 10 feet. The country rock is mica schist and gneiss containing cyanite and garnet. These rocks strike about east and west with a vertical dip. The beryl occurs in pegmatite, cutting the country rock with a strike of 15° W. and a dip of about 70° W. The pegmatite is about 3 feet thick and incloses a quartz streak or vein 1 foot thick parallel with its walls through the whole distance opened. A quantity of mica was found along this quartz vein in the work, and for this mineral the prospect was in part opened. Mica crystals 6 inches in diameter were found, but the quality and quantity could scarcely be considered of commercial value. Golden, yellow, greenish, and colorless beryl crystals were found. The beryl occurs along the contact of the quartz streak with the feldspathic part of the pegmatite chiefly in granular to coarsely crushed glassy phases of the quartz. Black tourmaline occurs in the pegmatite, and some is associated with the beryl in the quartz. The largest beryl crystal found is reported to have been about 3 inches thick and 18 inches long. A section of this about 3 inches long was seen at Nathan Barnes's house. It wras light-colored, mostly opaque, and not of gem quality. Small yellow to golden beryl crystals with fine clear portions were seen, indicating the occurrence of good gem material in the vein.
The presence of another pegmatite 15 feet west of the deep pit was shown in a small prospect pit.
At the prospect on James Chapman's place, formerly owned by Mike Swim, 1-3/4 miles N. 15° E. of All Healing Springs, a pit, now nearly filled up, 10 or 12 feet deep, was made on a pegmatite deposit. A vein striking about N. 25° W. was found inclosed in a gneiss of granitic nature. The presence of hard fine-grained biotite gneiss debris around the dump causes uncertainty as to whether the country rock may not be biotite gneiss injected by granite and not granite gneiss. A couple of hundred yards west of the prospect the country rock is cyanite schist. The pegmatite incloses a quartz streak about 1 foot thick. This quartz is mostly glassy and crystallized and some is smoky brown. The feldspar occurs in rather large masses, and a rough crystal with a cleavage face 8 inches across was seen on the
Ch. 3: Precious Gem stones in 1912 Page of 93 Ch. 3: Precious Gem stones in 1912
Table Of Contents bullet Annotate/ Highlight
US Geol. Surv. 1912. Gemstones, Metals.
Suggested Illustrations
Other Chapters you may find useful
bullet Tag
This Page