Montana “Diamonds” Quartz Crystals for Rockhounds!

Dead center in the great wide state of Montana, a deposit of quartz crystals can be found. Typically double terminated, squat crystals with very short c-axis, these come in clear, milky and smoky and available for people of all ages to find!

Photo of Quartz Crystals from Judith Peak Montana

This photo was used in the October 1971 issue of Gems and Minerals Magazine. This shows how they can be confused with actual diamonds, with their form.

There are dozens of locations around the world where quartz “diamonds” are produced. You see, people want diamonds. Marketing has told us how desirable they are, how they signify love. Just wait until the November through March, non-stop jewelry store commercials pushing whatever diamond scheme they have this year on everyone. In 2014 it was those terrible “chocolate diamonds” which are one step above industrial grade. The truth is, there are way more diamonds in the world than there will ever be a need for, so it is an artificial market kept afloat by you and me. With that in mind, a random that has very little knowledge about minerals can pick up a double terminated, squat quartz crystal and think “DIAMOND!”. This gives the name to so many deposits. Cape May New Jersey Diamonds, Herkimer New York Diamonds, Montana Diamonds, Pecos New Mexico Diamonds, Pakistan Diamonds, Tibetan Diamonds…all…quartz. Well, everyone loves quartz crystals, so hey, even if someone was disappointed that they didn’t find diamonds, us rockhounds are happy with what they found!

Montana Diamonds are found about 20 miles from the town of Lewistown Montana, nearly smack dab in the middle of Montana. On the top of Judith Peak, an open area for collecting with hand tools, an abandoned radar installation is located. All of the road construction and removal of trees and overburden for the buildings has uncovered ample ground for searching and rockhounding. At an elevation of 6,386 feet above sea level, an igneous deposit of rhyolite has been pushed up to the surface. The rhyolite cools at different rates, the slowly cooling rock giving more time for the quartz crystals to grow larger. This deposit hit the right notes, leaving a layer of rhyolite that contains these well formed crystals.

Map with Judith Mountain Peak pinpointed

The Judith Mountains are located in Central Montana. Judith Peak is about 20 miles outside of Lewistown.

Satellite map of Judith Peak Quartz Crystal Location

The pinpoint on the map shows Judith Peak and the pin covers up the main collecting area.

Judith Peak

This area is a great place to start prospecting – This is home to an defunct US radar installation.

In the USGS publication Geology and Mineral Resources of the Judith Mountains of Montana By Walter Harvey Weed, Louis Valentine Pirsson it is written about this area in 1898! (This book can be downloaded as a PDF by clicking this link)

Judith Peak itself is composed of quartz-bearing porphyry…The small, angular light colored flakes compose the crest and slopes. Pine trees grow thickly upon it, and in places they have been burned and the porphyry has been reddened or blackened by the fire.
On the north side of the slopes fall away into several steeply descending, half-funnel gulches. The angles of slope of the broken porphyry is extremely steep, and the gulches have almost the aspect of amphitheaters. Farther down the blocks of the broken porphyry naturally becomes larger.
Almost at the summit of Judith Peak, a few hundred yards north-west, the porphyry appears crushed and filled with narrow quartz seams, which are stated to carry low values in gold. Southward from here, although the porphyry is greatly rotted and broken down, it can be seen that there is a gradual increase in the number and size of the quartz phenocrysts until,…these quartzes assume a large size, the phenocrysts being often an inch or more long. The quartz crystals weather out as pebbles, and very perfect specimens may be obtained

Collector at the rhyolite deposit at Judith Peak Montana 1971

In this photo from the 1971 October issue of Gems and Minerals, you can see a collector searching for quartz crystals in the rhyolite.

Well over 100 years of collecting quartz from this location and yet…there is still more to be found! So, if you find yourself in Montana, right about dead center, you’ll be close to some fantastic quartz collecting!

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