The Great Fresnoite Discovery of 1998
A Summer of Hard Work Brought Him Unbelievable Rewards
by Scott Kleine, Gem Finders International
Photos by Scott and Harry Kleine, Bob Keller

Author Scott Kleine finds a cabinet fresnoite specimen in Pocket Zone #1 at the Junnila property.

The Junnila property, located in San Benito County, California, contains a little-known deposit that has previously produced only small amounts of benitoite, scattered fresnoite and a mix of crystalline zeolites. Over the course of the summer of 1998 I organized and operated a substantial, heavy-equipment mining operation on this property. This effort produced new pockets containing superb fresnoite crystals, the largest being 2.2cm. These are considered the finest-known examples of this rare and aesthetic species.

History of the Junnila Property

The Junnila property has been mined intermittently for the last several years. Liza Junnila and Bill Larson mined the top of the deposit with the use of a D-8 Cat. It was reported that approximately 500 benitoite specimens were found during that period. The first reported fresnoites were also discovered during this operation. (The quality of these remains unclear.) Other species, such as natrolite, joaquinite and analcime were also recovered.

Anything of interest exposed by this work was quickly snapped up by participants in later fee-digging tours. Afterwards, the quality of the specimens found quickly diminished. Upon my first visit to the mine, in May of 1997, very little was to be found as the mine had not been in operation for years and the collecting areas were well picked-over. Some beautiful, multicolored fluorescent specimens of heavily included benitoite, albite and calcite could be collected, as well as some very rare, broken/contacted crystals of yellow and, even more rarely, pink fresnoite. But, overall, the trip was more of a scenic adventure than a specimen-producing trip. I felt, however, that the property had much more to offer if some significant new exposures could be made.


A fresnoite crystal shown under daylight above left, and fluorescing under shortwave UV light above right.

Then, in the middle of October 1997, John Veevaert wrote to tell me about a surface pocket of small, fluorescent fresnoite crystals he had recently found there at night. Motivated by this information, I drove to Liza's house and asked her if I could go to the mine and collect. For a nominal fee, I was allowed in for a weekend.

Once at the mine, I followed John's instructions, located the spot where he had made his discovery and began a concerted effort to expose more fresnoite. Halloween night I found a number of contacted, but colorful, fresnoite crystals with my shortwave, ultraviolet light. Some of these specimens had undamaged, though small, fresnoite crystals on matrix. I was elated!

The next day I gave the mine a good going-over and realized that it had a lot more potential than I had first thought. Later that day, Liza visited me at the mine and, to my amazement, mentioned that the property was about to be put up for sale.

Shown at left is the fresnoite mining project, mid June, 1998.

"Wow!" I thought. "What an experience it would be to own and mine this property myself!" After careful consideration, I sent a proposal to Liza. It was accepted. By the end of the year, all of the contracts had been signed and signatures notarized. I now had the full lease to my own fresnoite and benitoite mine!

Location and Geology

The Junnila property is located on a 300-acre parcel of deeded, private property. No unauthorized visits are allowed. Access is made by driving eight miles up the Clear Creek Recreational Corridor, off Los Gatos Creek Road, into the heart of the San Benito Mountains. The nearest towns--Coalinga and King City--are each about 40 miles away.

The general region surrounding the property is composed of varying grades of serpentinized basalts, contact-metamorphic bodies and islands of Franciscan phyllites and schists. Several unique, highly mineralized deposits occur within a few miles of the mine.

Of the 300 acres comprising the Junnila property, only a few actually contain the specimen-bearing deposit. This is hosted in a series of bedded Franciscan phyllites and schists, which have undergone several episodes of mineralization. First emplaced were the blue schist facies, which host benitoite, strontio-joaquinite and neptunite. This rock type occurs as extremely hard, tough, resistant dikes which break apart into log-shaped boudins.

Some time later, a series of important geological events took place at the site. Along the southern edge of the deposit, a major strike-slip fault formed. This juxtaposed a huge body of serpentinized basalts next to the Franciscan phyllite-and-schist hosted deposit--the Franciscan rock types occurring as the footwall and the serpentinized basalts as the hanging wall.

Although the circumstances of the fresnoite's formation are not yet completely understood, I have strong reason to believe that the fresnoite formed from fluids flowing up, along the scarp of the serpentine fault. A 2-foot-wide reaction boundary of clay alteration occurs along this zone, providing evidence of significant, hydrothermal-fluid flow and rock alteration in the geologic past.

The titanium source for the fresnoite was derived from the serpentines along this reaction boundary. Only a single, heat-altered brown benitoite was found anywhere near these structures.

Specimen-Quality Species

Associated Species

Replacements

Pocket Descriptions

I located and collected at least seven significant fresnoite-bearing pockets at this site. Three of these occurred within the Mother-Load Pocket, while the other four were located in Pocket Zone #1.

Pocket Zone #1 was discovered along an east/west-trending, high-angle structure. Upon its discovery, a series of natrolite-flooded cavities were observed, leading into parallel sets of open, analcime-lined, fresnoite-bearing pockets. Several small (3cm to 5cm) crystalline cavities were collected, along with four other significant pockets up to 20cm long and 3cm wide.

This pocket zone had a rich assemblage of unexpected species, including: fresnoite; analcime; calcite-pseudomorphic-after-aragonite; chrysocolla-pseudomorphic-after-copper; galena; calcite; and gemmy, prismatic natrolite crystals. One fantastic cabinet specimen showed all of these species except galena, and fluoresced four different colors under shortwave ultraviolet light.

Fresnoites from this pocket zone were of superb color and beauty. Crystals ranged from 0.2cm to 1.2cm, and had a very rich, two-toned color. Some crystals showed rich, salmon-pink hues. The largest matrix, pink-dominant crystal from this zone was 1cm wide and displayed excellent luster.

While crystals were found detached from matrix, most fresnoite found on matrix had pleasing associations of white analcime. One pocket of full-pyramidal fresnoites up to 1.2cm was found within three feet of the serpentine-fault contact. Two superb cabinet specimens, along with a number of other fine examples were ultimately recovered from this rich zone.


Above, the 'Great Fresnoite Twin' Crystal from the Mother-Load Pocket.

The Mother-Load Pocket Zone occurred along a semiparallel, high-angle structure, only three feet north of Pocket Zone #1. By far the largest vug in this zone, the Mother-Load Pocket, produced 80 percent of the best fresnoite recovered. This huge, lenticular 1-meter-long by 1.3-meters-high by 5cm-wide cavity produced one flat of topnotch, matrix fresnoite specimens. From this pocket, three fresnoite crystals were collected which met or exceeded 2cm--the largest an incredible 2.2cm! Two of these huge crystals were found off matrix and one amazing 2.lcm, twinned crystal on matrix.

All of the fresnoites collected from this pocket occurred as detached crystals, thumbnails or small cabinet specimens. Sorry to say, no true cabinet specimens were found. Specimens with three or more fresnoites on matrix were found, along with some that had up to eight! The most unusual fresnoite specimen observed in this immense pocket consisted of six interpenetration-twinned crystals.

Most of the fresnoite specimens occurred on the crumbly, heavily brecciated footwall and were coated with stubby natrolite crystals. Only four examples were found on the hanging wall, all of which had excellent associations of large analcime crystals and/or strontio-joaquinite. It was interesting in that the analcime crystals on the foot wall were much smaller and lower-profile than those on the hanging wall. The only other material found was calcite-ps-aragonite.

My Mining Project

At left, Harry Kleine, Scott's father, collecting in rich, fresnoite bearing structures in Pocket Zone #1.

Once I had the lease to the property, I had a lot of work to do! I had to find a good backhoe to rent and get people signed up for collecting tours. My dad pitched right in and bought an inexpensive, portable tent-trailer, made a kit for an outhouse and found a table, chairs, water jugs, gas cans and all of the other amenities of basic life needed for a three-month stay in the desolate, though scenic, San Benito Mountains.

Finally, the time came. I drove to Fresno and rented my new Case-580 backhoe. I had a Low-Boy rig to take it up as far as the driver could go, and then walked it up the last eight miles of dirt road to the property. My dad towed the tent-trailer with a truck he got specifically for that task. It was a tough trip up to the mine, and I had to pull my dad's truck out of a few holes with the backhoe. But by the end of the day we'd made it! Once we'd arrived, Dad immediately began to set up camp, while I went right to work, using the backhoe to make a series of fresh exposures in the deposit, in preparation for the upcoming Memorial Day collecting tour. I carefully scraped away the loose muck and exposed the long-buried specimen-bearing rock underneath. This was a dream-come-true moment for me: a goal I had worked toward diligently for six months!

At right, fee digging activities during May, 1998.

On Memorial Day weekend, 15 people came up for the initial fee-dig. On the very first night of collecting, a beautiful fresnoite pocket was discovered. This was a good sign, as I had barely scratched the surface of the deposit. It also made for a good, first fee-dig tour. At that moment, I felt that all of my original intuitions about this deposit had been right on!

Within the first two weeks, as I continued work on the first six-foot-high bench wall into the deposit, I began hitting small pockets of contacted, but colorful, partial crystals of fresnoite. As the days went on, the pockets grew increasingly larger, until I discovered a 15-foot-long string of separate, high-quality, specimen-bearing fresnoite pockets. This area was christened Pocket Zone #1.

At left, mining along the serpentine-Franciscan fault boundary.

As I continued to mine this zone, the quality of the fresnoite sharply declined when I drew within a few feet of the serpentine fault. At the contact of this massive structure, all traces of fresnoite mineralization vanished.

Concerned about where to go next, I spent two days removing all of the surface muck from the floor of the pit, where Pocket Zone #1 used to be. I persistently cleaned a 10-foot by 15-foot surface area, until the white analcime and natrolite structures were clearly presented out of the dark-gray phyllitic host rock.


Mapping the floor, where Pocket Zone #1 used to be. Red flags indicate exposed fresnoite pockets. The yellow arrow points to the yet-to-be discovered Mother-Load pocket, a mere 2 feet below this surface.

I then coordinated with AZCO, a Canadian mining company which happened to be concurrently sampling the Gem Mine, just a few miles away. I found the staff very friendly and willing to help me with my mapping needs. I arranged to have the 10-foot by 15-foot fresnoite zone mapped at a 1-to-24 scale, and the whole deposit mapped at a 1-to-240 scale.

The interpretation of the resulting maps led me to a localized zone of concentrated fresnoite mineralization. Using the backhoe to trench alongside this zone and, subsequently, working carefully by hand over to the zone, I exposed an incredible 3-foot-high wall of 2-inch analcime crystals! This was the beginning of the Mother-Load Pocket! This was a very exciting time of discovery.

After digging vertically through the Mother-Load Pocket for almost 8 feet, I came across a crumbly, brecciated pocket of loose analcime crystals coated with rich black soil. One of the first pieces I picked up looked like most of the others in the pocket. But, as I hefted it, I noticed that it had an unusually high density. I raced to the camper and washed off what I immediately dubbed "The Fourth-of-July Crystal"!


Above, the 'Fourth-of-July' Crystal from the Mother-Load Pocket.

Within a few days, all of the specimen-bearing ground had been very thoroughly collected and I backfilled the hole where the Mother-Load Pocket Zone had been, ending collecting at this site.

By now it was the end of June. Over the next three weeks, I began a long period of serious rock-moving, pulling one 5,000-pound to 9,000-pound blue-schist boulder after another out of the solid dikes. It was grueling work, as the temperature was over 100 degrees every day.

I would occasionally find a boudin that contained some stony benitoite, but little else. I continued to push the bench northwest, until I had worked completely through the deposit. It was now the middle of August, and time to tear down our camp, drive the backhoe out and go home. Reflecting back, I realized that I had the privilege of making over 50 new friends who had come by for my fee-digs.

Specimen Preparation

When I got home, I immediately began the process of cleaning and trimming all of the fresnoite I had collected. I soon realized this was going to take a lot of time and energy. Many of the best specimens from the Mother Load Pocket had a heavy coating of late-generation natrolite, which had to be removed. But after studying up on my cleaning agents, I found that fresnoite, analcime and natrolite were all soluble in most acids. After a lot of testing, I discovered that, by selectively waxing the analcime matrix and only leaving the natrolite-coated fresnoites exposed for brief periods in dilute, semisaturated HCl, the natrolite could be safely removed from the fresnoite crystals.

Other specimens had very hard clay stuck to them. I learned--much later--that this coating would only come off after months of soaking in pure, pH-stabilized water, with regular ultrasonic cleaning cycles and a lot of elbow grease. But I found it a pleasure to work with these rare, aesthetic specimens of high quality, to expose their optimal natural beauty.

Conclusion

My mining operation at the Junnila property produced a number of world-class fresnoite specimens. Other species, which were also found, turned out to be much more varied and unusual than I had first imagined. I wonder if any future mining on the property will result in more significant mineral finds.

I hope this account of my experience will inspire you to try your hand at mining. Good hunting!


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