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Mine Tales: Arizona's world-class onyx
Mine Tales

Mine Tales: Arizona's world-class onyx

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Onyx marble deposits just north of Mayer and adjacent to Big Bug Creek, in Yavapai County, have proven world-class.

From these fields discovered in 1889 by George B. McCann and Joseph Mayer, several samples of onyx were removed and sent to E.V. Roddin’s jewelers in Chicago and to a Professor Price in San Francisco. The consensus was that the specimens’ qualities were superior to those of Mexican onyx.

Multiple claims followed in the renowned Mayer onyx fields.

Both Joe Mayer and his associate William Owen “Bucky” O’Neill, who paid $150 for a one-third interest in the mine and served as president of the Arizona Onyx Quarries, were some of the original claimants and promoters.

O’Neill was involved in other mining ventures including serving as vice-president and general manager of the Grand Canyon Mining Co.

He was instrumental in having onyx samples shipped to New York, Chicago and Boston for display. O’Neill and his partners sold their shares of the mine in 1893 for $200,000.

As a captain, O’Neill later commanded Troop A in the Rough Riders during the Spanish-American War. While rashly exposing himself to enemy fire during the battle at San Juan Hill, he was struck down by a melee of Spanish bullets after having proclaimed to his fellow soldiers, “The Spanish bullet was never molded that will hit me.”

The onyx marble sometimes referred to as travertine is found as low dipping veins up to 3 feet in gravel. Deposits in the Mayer locality range between 1 to 25 feet in thickness, covering in excess of 300 acres. Country rock is comprised of schist intruded by volcanic dikes. The onyx is found interbedded among the blocks of country rock as a cavity filling in lavas.

Its coloration ranges from amber, yellow, brown and white to deep brownish-red and green.

High-grade onyx from this locality was hauled by wagon to Prescott, then shipped by rail to Dubuque, Iowa for refinement into ornamental items such as cameo brooches, book ends, carvings, countertops and paper weights.

Low-grade onyx was crushed and distributed to market for colored composition roofing and terrazzo flooring.

Classified as evenly banded agates, onyx and sardonyx are sought after, having qualities of being translucent and waxy.

Onyx, a variety of chalcedony, is derived from the Greek term for “fingernail,” on account of the width of the bandings.

The distinction between agate and onyx is in the colored banding. Agate has circular bands while onyx is a form of agate that has straight, parallel bands.

Sardonyx is a special variety having bands of sard or carnelian, a red form of chalcedony combined with white or black chalcedony. These bands alternate and are favored among sculptors who hand-carve figures at the junction of two layers of onyx.

Banding is due to the deposition of successive layers of lime carbonate. Color in the form of clouds and veins is caused by metallic oxides, most notably iron releasing brown limonite or deep-red hematite in the calcite.

George C. Underhill managed quarry operations in 1897. He initiated the installation of a mill for sawing and polishing the onyx.

Extraction of onyx involved the use of 50-ton capacity derricks used to load the onyx slabs onto wagons.

The arrival of the railroad to Mayer the following year greatly expedited shipment of onyx, including $100,000 worth of material shipped to R.G. Dunn & Co. in New York City for building materials.

The Yavapai Onyx Mining Co. operated at the site for decades, extracting high-grade onyx from 10 quarries. An onsite geologic survey estimated reserves at over 2.5 million tons of high-grade material in the deposits and 3.5 million tons of low-grade material for crushing. Core drilling revealed a similar, if not greater, deposit lying underneath.

By 1926, a documented 1 million pounds of onyx were shipped to market. Some onyx from the Mayer quarries was used in the American automobile industry for decorative car detailing, including gear shift balls.

However, from the beginning of its discovery and throughout the 20th century, mining activity remained intermittent based upon market demand and company solvency.

A crawler tractor with a ripper and loader, an air track drill and a rubber-tire tractor mounted rock breaker (on a backhoe boom) are some of the mining equipment used to extract onyx for market at the mine site in recent years.

During the 1990s, road construction along Arizona 69 necessitated a cut through the onyx deposit. Hundreds of tons of onyx from the site were removed and sold by construction contractors to regional business interests during the process of making road cuts.

The site continues to operate today, supplying dimension stone and gemstone onyx to the world. Its overall value of 16 lode claims averaging 20 acres each is estimated at over $2.5 billion after quarrying, processing and shipping costs.

This, along with placer gold deposits in a creek bed on the property and a heavy underlying vein of copper below, will make this area an attractive investment for at least the next century.

William Ascarza is an archivist, historian and author of seven books available for purchase online and at select bookstores. These include his latest, “In Search of Fortunes: A Look at the History of Arizona Mining,” available through M.T. Publishing Co. His other books are “Chiricahua Mountains: History and Nature,” “Southeastern Arizona Mining Towns,” “Zenith on the Horizon: An Encyclopedic Look at the Tucson Mountains from A to Z,” “Tucson Mountains,” “Arizona-Sonora Desert Museum” with Peggy Larson and “Sentinel to the North: Exploring the Tortolita Mountains.” Email William Ascarza for a signed copy of his publications at

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