An Offer to Visit a Chrysoprase Mine

It happened that my friend Randy Polk, a top jewelry artist, was at a show looking for gem material with “gumdrop colors.” He found a dealer selling fine chrysoprase stone. The dealer also owned the chrysoprase mine and was looking for someone to help with publicity.

Randy told him about the articles I was doing for Rock and Gem. The owner, Ellie Christianos, got in touch with me and offered to bring Carol and me to Australia to visit the mine and write about it.

It took me a few seconds to say “Yes!”

Two months later we were at the mine.

Australian Chrysoprase

It may have been used by the ancients but the first productive deposit was opened in the Middle Ages in what is now Poland. This is the world’s largest deposit of chrysoprase which occurred in the ultramafic rocks which were the source of the nickel that gives chrysoprase its lovely green color.

The chrysoprase you see today is mainly from Queensland. That’s because the better chrysoprase deposits are in Australia in Queensland in the east and Kookynie near Kalgoorlie in the west.

The deposit near Kookynie was working full bore when I was there but the last I heard it is involved in legal matters and not producing. The mine is in the far Outback about 100 kilometers east of Perth.

Arriving in Australia

Carol and I were met at the Perth airport by Ellie’s lawyer who checked us into an elegant hotel before he took us to Ellie’s penthouse overlooking the Swan River.

After a day in Perth, we were flown to Kalgoorlie, a big gold camp with gorgeous Victorian-style buildings. The gold mine, an open pit and underground workings, was still operating. There our guide rented a car for the two-hour drive out to the mine, dodging kangaroos and emus on the way!

The road was dirt and crossed the outback desert. Many vehicles in the outback have what is called a “roo bar,” a heavy large steel fence-like bumper on the front to protect it from impact with kangaroos or cattle.

Chrysoprase, which is chalcedony with an assortment of nickel salts in it to give it a green color, formed in the thick veins of rock that make up the entire hill. Most of the rock is iron oxide goethite that’s not hard, so mining was relatively simple. They did not use explosives only a D-8 Caterpillar bulldozer with a huge ripping hook or finger on the back.

The ‘cat’ would traverse the hill up one side and down the other ripping up rocks veined with green chalcedony chrysoprase.

Following the ‘Cat’

The rocks were loaded with veins of green chalcedony that were broken into chunks by the dozer. The miners just followed behind the dozer with a hammer and buckets to gather the loose chunks of the green gem. In this way, they had mined tons of chrysoprase and the hill showed no signs of running out of gem material.

To collect, Carol and I followed the ‘cat’ picking and choosing the better dark green specimens and chipping off chunks of the better gem specimens. The only problem I had was choosing which pieces to pick up keeping in mind we were flying back to the U.S.

Once collected by miners, the gem-filled buckets of material were hauled off to another area of the camp and spread out for ease of sorting according to color and quality. The very best gem pieces were set aside for later pricing. The pieces of only good to average color were left in the open and priced lower.

I was told that area held no less than 10 tons of rough waiting for sorting and sale.

Choosing Specimens

When Carol and I had filled our collecting buckets, we took them back to camp and washed the specimens so we could sort through them. I set aside only the better pieces and returned the rest to the company stash. Later I returned to the hill and did more collecting in the untouched areas to get a better idea of the deposit and the material.

Ellie had already told us we could help ourselves. When I finally had what I thought was a fair amount of the best gem rough, I thanked Ellie. He expressed surprise at the small amount of gem chrysoprase I had.

When I mentioned my luggage problem, he offered to ship everything to me in Arizona so we added a bit more and he shipped it all.

I did spend some time walking around the area and noted several prospect holes where earlier prospectors had checked the deposit. It was pretty obvious the area was rich in potential as there were veins of chrysoprase exposed.

Visiting an Australian Pub

One evening, the miners asked if we wanted to go to a local pub. They piled us into a big 4×4 with a roobar and off we went at breakneck speed across the desert.

If there was a road I could not see it. We pulled up in front of a shack with a rusty corrugated metal roof and a single gas pump in front. This shack was the pub.

The building had two rooms separated by a liquor bar between them that faced into both rooms. Each side of the bar had four stools occupied by the dirtiest-looking miners I’ve ever seen. They worked in the local gold mine where the dirt and rocks are a rich brick red color. Water was scarce so washing was a sometimes thing. They were great guys, very friendly. They couldn’t stop telling stories and tales. One of them had just married off his daughter so he had to tell us all about the parade and wedding which was interesting in such a desolate area. A couple of dart boards hung on the wall and one wall had a heavy black line painted on it which was the high water mark when they had a rare rain storm. We had quite an evening there!

Chrysoprase Buyers

Another day a buyer from China showed up and spent a lot of time walking over the material in the sorting area. He was looking to make a big purchase. I learned they had two factories in China with about 7,000 women at lapidary machines carving objects of green chrysoprase, which I suspect was passed off as “jade.” I was amazed when he placed an order for 55 tons of the low-to-medium-grade chrysoprase.

When we left Western Australia we stayed in Sidney as Ellie’s guests. We checked out the zoo and the famous opera house then flew on to Hawaii for three days. When Carol and I got home, we immediately shared the chrysoprase with folks in our mineral club and gave the best pieces to Randy Polk who had gotten us the invitation. All in all, it was quite a rock hound trip!

This story about chrysoprase stone previously appeared in Rock & Gem magazine. Click here to subscribe. Story by Bob Jones.

The post Finding Chrysoprase Stone in Australia first appeared on Rock & Gem Magazine.

Chrysoprase Legend

There’s also a legendary tale about Alexander the Great, who believed he gained tremendous wisdom from this stone, and as such, wore it on his belt into each battle. That was until one day while crossing a river, he was struck by a snake, which caused the stone to be knocked off his belt and fall into the river. Unable to find and recover the stone, according to the tale, he never won another battle.

Where to Find Chrysoprase

Chrysoprase is found in several places on earth, including Germany, the United States, and Madagascar. However, the most known locality in modern times is the Marlborough region in Queensland, Australia. This stone is getting a bit scarce to find in higher grade material in larger size pieces, and pricing reflects that in the marketplace. Grading is also something to carefully consider when buying this material. High-grade specimens will be a solid color with no blemishes or inclusions and are highly sought after, so expect a much higher price when shopping for rough or slabs that fall into this category. There are other colors of chrysoprase, such as citron/lemon, and a pale variation from Indonesia.

Purchasing Material

When buying rough, it can be tricky to find large enough seams that don’t curl up in many areas (like a potato chip). This condition makes it a challenge to slab, so be prepared to hunt through substantial pieces to find a few that will yield a large enough area in the slab to cut cabochons. Sometimes you might end up buying thin seams and have to grind the top and bottom portions to gain enough space to cab. Since chrysoprase is an exceedingly hard material, ranking at a 6.5 to 7 on the Moh’s scale, it is best to hold off proceeding until you have changed your blades and wheels. I can’t express how valuable a fresh set of wheels are when working on this material.

Grading is also something to carefully consider when buying this material. High-grade specimens will be a solid color with no blemishes or inclusions and are highly sought after.

Cabbing Chrysoprase

When cabbing chrysoprase, a traditional six-wheel set up will work just fine, but if you can swap around the wheels, I highly suggest starting on an 80 grit steel wheel, then smooth it out on a 60 grit soft resin wheel. This approach will reduce the time and effort it usually takes when working on a chalcedony that is this hard. After smoothing out the edges and doming the cab, I like to move onto a 140 grit soft resin wheel, which removes all the deep scratches and makes it easier to finish on the 280 grit wheel and progress forward. While working the cab on the 280 soft resin wheel, you can continue to check for any existing scratches. It would be best if you did not move forward at this point until the scratches are gone.

One helpful trick to use at this point is to quickly run the cab over the 1200 grit wheel and then dry the cab completely. Being a solid color stone, if any scratches still exist, they will immediately show themselves by using the 1200 wheel. Once all the scratches are gone, and you can move forward, run the course like any other agate you cab and finish on a 14,000 grit soft resin wheel, or 50k if you have it.

Finishing Up

At this point in the process, your chrysoprase cab should render a brilliant glossy finish. You can use a small amount of cerium oxide on a leather buffing wheel to obtain a more mirror finish, but be cautious not to heat the cab in the process, as it may fracture from the heat generated.

Sometimes, leaving well enough alone is the best thing to do.

This What to Cut column about chrysoprase previously appeared in Rock & Gem magazine. Click here to subscribe! Story and photos by Russ Kaniuth.

The post What to Cut: Chrysoprase first appeared on Rock & Gem Magazine.

Recently, when I was slabbing a large Brazilian agate nodule, looking for some milky chalcedony within it, I chanced upon a druzy cavity surrounded by small dendrites. Fortunately, the cut was at just the right place for me to make a striking cab from the pattern. This piece has an opening where the druzy background is well exposed.

The shape of the rough slab allowed me to form the cab into a triangle. After shaping the cab, I had an inspiration to mount something between the top of the dendrites and the tip of the cab. I haven’t done much inlay into the front of a cab, so this was a great opportunity to learn how.

Task by Task

My first task was to decide what shape, size and material would look good with the overall shape and material of the cab. Due to the limitation of my skills and experience, I decided a round shape would give me the best chance of success.

I thought about using carnelian, lapis, chrysoprase or—my preference—gem silica. I couldn’t find any gem silica in my pile of rocks, so I chose chrysocolla. I decided that an 8 mm, round stone would fit the best. I trimmed the rough and ground it to shape. I then dopped it and finished doming the cab with my small sphere cup, mounted on my flat lap machine.

After shaping the small cab, I polished it in preparation for mounting. I took careful measurements on the larger cab to ensure the smaller one would be centered correctly. I started the hole with a 2 mm round diamond bur. Next, I used a round 220 diamond bur that was slightly smaller than the chrysocolla cab to make the hole for mounting it. Because the hole had a round bottom, it would need to be reshaped to form a seat for the cab. I used an inverted cone diamond bur so I didn’t inadvertently enlarge the hole as I made the stone seat.

Fitting A Cab Into Its Mounting

Fitting the small cab into its mounting took special care so that no gaps were left between the stones. For this step, I used a 400 grit diamond cylinder bur. The upper edge of the hole had a tendency to chip, especially if the bur was too coarse or I applied too much pressure to it. Slowly, I ground the hole larger, and checked the fit many times. Once it fit down into the hole, I checked the depth of the seat to make sure that the small cab was at the right height. Even with care, the upper edge of the hole, as expected, had some small chips.

I had allowed for this when I originally shaped the larger cab so it was just a matter of re-sanding over the hole to remove the chips. The final step was to mount the small cab with epoxy 330.

The post Bench Tips: Druzy dendritic cab with inlay first appeared on Rock & Gem Magazine.