an excerpt from Gemstones of Idaho by Alice Allebaugh
This excerpt from Gemstones of Idaho, written circa the late 1950s, was taken from a Monograph by Alice Allebaugh, Past President, Northwest Federation of Mineralogical Societies.
In the beginning, when the Earth's crust was convulsing in periods of thermal contracting and expanding, when mountains and valleys were being formed and violent alterations and adjustments were carving canyons and gorges, lakes and valleys, it was then nature was also creating for us a veritable jewel box. It is from these creations produced throughout the scale of time that the rock hobbyists, gemstone and artifact collectors draw from a seemingly bottomless well our wealth of minerals, fossils, artifacts and gems - from the lowly lichen, crinoids and trilobites to the fabulous opal and diamond.
Like the rest of the world Idaho, our Gem State, came into being from the Pre-Cambrian Epoch down through the Pleistocene and the Recent Epoch which occurred only some 20,000 years ago. I will not dwell on geology here for my subject is gems and minerals of Idaho, but without geology or some knowledge of it we would not fare so well.
Idaho offers to the collector of precious and semi-precious stones a bountiful field. The wealth of material in this state is becoming widely known, but so far has been explored only to a limited extent. Nearly every county in the state bears an abundance of material. Agates, jaspers, opals, agatized and opalized woods are found associated with the great lava flows that cover the southern part of the state. The northern part offers most excellent fossil flora in the great thicknesses of the sedimentary beds of the Latah formations. Only a few of the better known and important localities are elaborated upon here.
In Owyhee County, which is one of the largest counties in the state, hobbyists have gathered a bountiful yield of beautiful red, yellow, green and mossy jasper of unexcelled quality. The area is noted for its gorgeous pink and white plume agate and fine gem quality common and fire opal, most of which occurs as amygaloid filling steam holes and cavities. There are also found in this same area agates of all types and colors - banded, scenic dendritic and sagenite, polkadot, smoky and moss types. Succor Creek on the western edge of the county produces the rich two-toned red and green quartz plasma, as well as the familiar elliptical and round shaped nodules known as thunder eggs, and whose cavities are filled with agate or crystal formations. Quantities of agatized and opalized wood are found scattered over the plateaus of this region, the majority of which is of a quality well adapted to the making of polished slabs and cabinet specimen pieces. Fine rock crystal quartz is found associated with the ores on the dumps of many of the mines in the Silver City District in this area, amethystine being among the most desirable.
In Gem County beautiful fire opals are found in the lava flows of Squaw Butte near Emmett. These opals, while rather small, are of salmon pink or cherry color, showing much brilliance and play of light. A few have been found in this deposit large enough to cut into gem stones. Fortification and water agates of light blue color are found close to the opal deposits. Willow Creek in this county has a sizable deposit of agatized and opalized wood in good quality, while further up the creek is massive opal varying in color from deep red through salmon pink to white and pale blue, and which is referred to by hobbyists as Wilkite, so named from Willow Creek on which is it found.
Agates of many colors clear and citrine quartz crystals, and petrified wood are found in abundance in Washington County. Some of the agates, when cut into thin slabs, show rainbow iridescence. The silicified wood found on Manns Creek northeast of Weiser is of particular note. The grain, being very prominent, resembles natural oak to a marked degree and is the color of bright yellow oak. In the Beacon Hill area are found the famous Beacon Hill nodules, which are scenic, dendritic and crystal lined.
At Ruby Flat near New Meadows in Adams County a few rubies and fine pink garnets have been found, and claims have been made that diamonds have also been picked up. Sapphires and corundum crystals ranging from quite dark to very light blue through lavender to colorless are there, a few showing slight asterism.
Custer County, which lies in the heart of our mountainous area in the central part of the state, and part of which is seemed off by the Salmon and Lost Rivers, is a rock hunter's paradise. Transparent quartz crystals line the chalcedony geodes which time and the elements have weathered out of the lava, some being as much as fourteen inches in diameter. Agates of every type are scattered over the area, as well as red, yellow and green jasper in abundance. Petrified fossil leaves and stems, and even a large petrified forest, are found in the tuffaceous formation. Near the East Fork of the Salmon River a beautiful variety of crypto-crystalline quartz having a combination of blood red, sand, white and brown onyx exists, while near the town of Challis is a rich deposit of black limestone containing great numbers of Favosites coral. Also, just south of Challis, occurs one of the rarer zeolites, MORDENITE, which seems to be present in greater abundance and better specimens than in any other known locality.
Only a few of the better known and larger areas of gemstone material sources have been mentioned here, but it might be well to mention a few more localities from which we add to our collections: amethyst from near Hailey in Blaine County; opal and opalized wood from Lincoln and Gooding Counties; fire opal and the much sought after star garnets from near Moscow in Latah County; and the large fossil deposits near Whitebird in Idaho County. The fossil beds of Hagerman Valley in Gooding County are also famous, for in the material from this area scientists have been able to reconstruct a living record of the dead.