THE BACKBENDER’S GAZETTE

26 intrepid HGMS members met at 8:15 on Saturday morning, January 17, at the Martin Marietta Midlothian Cement Plant. This used to be a fairly regular field trip, but hasn’t happened since before COVID.  Mike Sommers made the arrangements for us to go. We were going to look for pyrite.  The quarry has 2 sections. One part is limestone and that is where the pyrite is found.  The other part of the quarry is shale and contains marine fossils.

Some of the members traveled to Midlothian, about 4 hours from Houston, on Friday night before the field trip. A small group met for dinner and had a great discussion about what to expect.

We were met by Kristen, Mike’s contact from the quarry, and 5 or 6 other employees.  They invited us inside where they had safety gear ready for us.  We had to wear safety vests, hardhats, safety glasses and gloves.  They also had coffee, donuts and a local delicacy – fried biscuits- which were biscuits filled with sausage and of course, deep fried. Mike had samples of different configurations of pyrite nodules to show us what to look for. He also explained how each was formed.

We each got into our respective vehicles and caravaned out to the dig site. Everyone got out and started looking around.  After a few minutes, Kristen called us together and said they were going to take us to a different spot since they didn’t see much pyrite. We got back in the vehicles and went about 4 minutes further into the quarry.  A note: There were many ‘sort of’ roads that crisscrossed the quarry. It would have been very easy to get lost without our guides.

Some very simplified geology – limestone and shale are both sedimentary rocks that form from ancient inland seas.  Limestone is calcium carbonate and forms from the shells, coral, algae and other marine life.  It is an excellent host since it is very porous. It is also permeable.  The pyrite forms from a combination of iron and sulfur in the limestone.  Shale is often formed in the same environment but is basically layers of compressed mud. It is not permeable. Fossils are found in the layers.

There were high mounds of limestone, dirt, and clumps of rocks and matrix.  The incline was really steep – a veritable slippery slope. Club members just started climbing and soon had the hillside covered. We were told that the larger, more defined specimens were at the top. The pyrite had more chances to weather as you got lower. The pyrite was noticeably different from the limestone and easy to spot.  You could just pick it up in some cases or nudge it out of the limestone with the pick end of a rock hammer.  I was able to get to most of the things I collected just using my long-handled rock scoop.  I stayed on the flats, but some people found pyrite and nice fossils at the top.  I saw some people set up mini mining operations, really digging things out.

The employees had lots of information and were eager to share. They were also very helpful in pointing out pockets of pyrite. I learned all kinds of things. They thought they had about 45 years of material to take out at their present rate.

One side of I-35 is clay (from shale), the other is limestone which is a perfect mix for making cement. That’s why that area has a lot of quarries. The limestone has too much pyrite to use for concrete but is perfect for cement.

The starting salary at the quarry is $30 per hour. As the employees gain skills, the salary increases. $40 an hour is fairly common.

The land is reclaimed. It is filled back in to the original elevation with a profile similar to the original lay of the land.  They let nature take its course – birds, wind, animals replant the area. Several states have to put the land back exactly the way it was, down to planting cactus at the original locations.  Luckily for us, Texas is not one of those states.  They just have to approximate the original appearance.

After a half hour or so, we given the opportunity to go to the fossil site.  Some of the group formed another caravan and went to the shale side.  That was an entirely different kind of dig.  Paleo people sat and carefully sifted through the shale looking for sharks’ teeth and shells.  Several large sharks’ teeth were found. Some people were finding were calcite crystals. I found an inoceramus clam.

Beading – Second Saturday, 12:00 PM  

IMPORTANT NOTICE:  Starting in March 2026 the Beading Section Meeting will start at 10 AM rather than Noon.  We will meet from 10 AM to 1 PM and those who choose to can join us for lunch afterwards.

NOTICE: Do you have a bracelet or necklace that needs restringing?  The Beading Section will carefully restring your piece at an hourly rate of $15.00 + materials.  Contact Beading @HGMS.org to make arrangements.  All funds will go to the Beading Section.

Always bring beading mat, scissors, wire, wire cutter, round nose and needle nose pliers, thread, and beading needles if you have them.  

Find out more about the Beading Section!

Lapidary and Silversmithing – Third Monday, 7:00 PM

The next meeting will be on February 16th at 7:00 pm. We will explore opal cutting and polishing! Bring your opal to show off

• Last month we made cowboy hat earrings with a hydraulic press and special jig.

Email Lapidary@hgms.org if you have questions, and check out the Lapidary and Silversmithing Section page.

Day Light – First Wednesday, 12:00 PM

The Daylight Section meets the first Wednesday of the month from 12 to 3 PM.

The next meeting of the Daylight Section is Wednesday, February 4th at 12 PM.

Our February project of a copper Viking Weave bracelet, will be taught by Margaret Hardman-Muye.

While the picture shows silver, this will be a copper project. Registration will be limited to 8-10 participants. The fee is $5.00.

Mineral – Third Wednesday, 7:30 PM 

The next meeting is Wednesday, February 18th at 7:30 pm.

We will continue the Common Minerals program with Celestine. There will be lots of appropriate specimens.

There will be a door prize and snacks and a small Silent Auction. Come see some rocks and ask questions!

Zoom link for the meeting:

https://us02web.zoom.us/j/4517997588?pwd=SnZjckZBTnRMbHRxZitScE9WU3RWUT09

or

Meeting ID: 451 799 7588
Passcode: 623955

If you’d like to join the Mineral Section email list, send an email to mineral@hgms.org and ask to be added.

For those of us who cut slabs, to use in making cabochons or for other purposes, getting the right thickness is a never-ending process.  For most cabochons you want a ¼” thick slab, but other thicknesses are needed for different purposes, thicker for a higher dome and thinner for adding a quartz cap or a basanite back.  The four slab saws in the shop all present different problems getting the right cut.  The 18” and 20” HP slab saws take about 7 turns to get ¼’ and the 24” saws are each different numbers of turns to get that thickness.  Many times, despite our best efforts, the slabs get cut too thin or too thick.  So how do you handle this problem?  One way is to cut a slab the correct (or almost correct) thickness and use it as a guide for the next slabs.  Or have a piece of wood more or less than ¼” thick.  Not satisfied with this hit or miss process?  There is an answer.

Last October, when I was at the Austin clubhouse for the SCFMS convention meetings, I was given a tour of their “Slab Shed” by the outgoing president, John Conner.  I saw some plastic sticks stuck to a piece of metal by magnets with thickness dimensions on them, including the usual ¼’ thickness.  John told me they were slab thickness gauges and that they had been made up for the Austin club by one of the members using his 3D printer.  I expressed an interest and he emailed both of us by way of introduction.  Fast forward a month to November, when I was in town to give a talk to the Austin club at their general meeting.  The next day we were back at the AGMS clubhouse, and I got to see the slab saw guides in action.  They helped a saw master cut identical thickness slabs for an Austin Community College class on cabochons.  After that experience I reached out to the club member, and he agreed to print a couple sets of gauges for HGMS in three thickness sizes.  He also sent me a diagram on how to use these gauges properly.  Eventually the gauges arrived and will be delivered to the club shop in February with the diagrams.  Due to their small size, they will be stored in a cabinet and brought out for use by the shop supervisors.

David Pawek reports that the club received a shipment of grinding wheels for the grinding stations in the Shop, enabling him to replace damaged and worn-out wheels.

Wonderful news! Now let’s keep them in good shape by remembering NEVER PRESS A SHARP EDGE INTO A RESIN WHEEL! That’s what metal 100-grit wheels are for.

A sharp edge can tear the surface of a resin wheel, where the diamond coating resides, making it useless.

A three-person team will reassess the Ventilation Project to protect our members from fumes in Shop spaces. Lillian Skogsberg and Debbie Seid have expressed interest in being involved.

BEZEL  CLOSER

A bezel closer is a steel punch that makes quick work out of pushing the metal down over a round stone and burnishing it. It works with regular bezels, with tube settings, and with prong settings.  Stones can be set in as little as 30 seconds.

The working end is a concave cavity that fits over the bezel or prong setting and is pushed and twisted to capture the stone. Sets can be purchased but are expensive and contain many sizes you will probably never use. If all you need is one or two sizes, here’s how you can make them yourself.

Find a round steel rod or bolt a little larger in diameter than your bezel cup or prong setting. Cut a 5-inch length. File both ends flat. Locate the center of one end, centerpunch a divot, and drill a small pilot hole about 5 mm deep. Remember to use a little oil as lubricant when cutting steel.

Select a ball bur a bit larger than the bezel. Enlarge the pilot hole to a full hemispherical cavity. Test for proper fit with your bezel. Bezel should first contact the cavity about a third of the way in. When the size is correct, polish the cavity using Zam on a length of chopstick in your flexshaft. If the tool is not polished, it will leave scratches on your bezel or prongs.

When using the tool, the first step is to capture the stone correctly. I usually work by hand and push the punch straight down over the bezel or prongs. This causes the metal to start bending over the stone. The next step is to inspect the stone with a lens to be sure it is staying level. Repeat until the stone is seated on its bearing and can’t move anymore.

Finally, force the metal down onto the stone uniformly all the way around. While this can be done by hand, I often gently tap the punch with a hammer. Finish by twisting the bezel back and forth to burnish the top of the bezel.

BENCH  SHEARS

When cutting sheet metal, it’s quicker and easier to use a set of shop shears as compared with using a hand saw.  The cut is not as precise, but many times you don’t need that. Shears will easily cut up to 24 gauge sheet, and some will cut 22 or even 20 gauge.

Current prices for shears run from $13 – $36 in jewelry catalogs, and the Joyce Chen scissors recommended on some jewelry blogs run more than $20.  But I found  cheaper alternatives at the 99 Cent Store for use in my classes. They’re great for cutting bezels, trimming around a bezel cup and cutting a piece off a larger sheet.

Can I Interest you in a Field Trip to South Texas?

Ten months ago, I stumbled by chance upon a recently uploaded YouTube video titled “Ancient Landscapes of South Texas: Hiding in Plain Sight” (https://youtu.be/398URwHw8VU).   I was swept up in a riveting geologic history of the Rio Grande Valley that spanned 40 million years and made me want to visit the fascinating sites featured in the video.

Originally a feature film produced by the University of Texas Rio Grande Valley, “Ancient Landscapes” was created to educate the residents of the Valley about the landforms and geologic features of the places they see in their everyday lives.  The film and coordinated exhibits toured venues in the Valley for two years after release.  Afterward, it was converted into video and uploaded to YouTube.  The film’s high production values and lush, engaging viewing experience translated well to video.

There are too many topics from the film to survey here, but I can’t resist describing the roadside feature that captured the enormity of geologic processes 27.4 million years ago.  Many of us have collected petrified wood here in Texas that originated in the Catahoula Formation.  Some of us have read that the silica that enabled the fossilization of trees in the Catahoula was ash carried on prevailing winds from enormous volcanic eruptions during the Oligocene and Miocene in what is now Mexico.

Imagine standing next to a 20 meter deposit of white Catahoula ash capped with the Goliad Formation:  seventeen meters are above the surface and LIDAR confirms there are three meters below the surface.  Geologists estimate that this exposure was deposited in a single event that occurred within several days to two weeks.

It would have buried miles of sabal palm forest along 136 miles of coastline.  That same ash fall contained the uranium that has been mined for years near Three Rivers, Texas.

I hope you’ll view “Ancient Landscapes” for this and many more examples of the geology of the Rio Grande Valley.  A journey from Houston to the Valley and back could be planned to visit a number of interesting geological (and paleontological) sites along the way.

If the film sparks your interest you can email president@hgms.org and I’ll send you related links (including a second, related video and several papers) that I researched after becoming entranced with the topic.

Chris Garvie’s recent program at the November ’25 General Meeting reminded us that in the ‘90s HGMS used to routinely have field trips that went as far afield as Alabama, the East Coast and similar distances.  Maybe a visit to the Valley could re-establish our former ambitions!

As I write this article, we are expecting an arctic front to pass through the Dallas area. Each year, in the Dallas area, we get one, two, or sometimes more ice storms associated with these arctic fronts. We dread them. Ice and packed snow accumulate on the roads. Living as far south as we do, the cities have few (if any) snow plows and limited equipment to remove Ice. Sand is used on inclines and some intersections, and in the last few years, they have started treating major roads with a brine solution before the storm hits. Generally, we just wait until the sun comes back out to melt the snow and Ice to clear our roads. Travel can be treacherous.

So, what does an ice or snow storm have to do with rockhounding in Texas? First, let’s consider what a mineral is. A mineral is a naturally occurring, inorganic, solid material of a consistent chemical composition and a definitive crystalline structure. Rain is definitely not a solid; the solid form of rain (water) is Ice. Under the right conditions, Ice can form a definitive crystalline structure. It is certainly naturally occurring and has no organic material. In other words, Ice is the crystalline form of water, and it is a Mineral until it melts.

Terror Birds, or members of Family Phorusrhacidae, were predatory carnivores that lived primarily in South America from the Eocene to the Late Pleistocene. They were predators of open savannas, relying on excellent vision, strikes from claw and beak, and speed to catch their prey. They evolved in South America and a few species made it to North America after the formation of the Isthmus of Panama. Fossils have been found in Texas and Florida. Their extinction 2 million years ago may have been due to mammals introduced from North America, although possibly they persisted in some areas as late as 6000 years ago.

Possibly they were hunted by Native South Americans. Possibly they tasted like chicken!

Other large flightless birds are not Terror Birds. Ostriches, from Africa; Emus from Australia; Cassowaries from New Guina, Australia and nearby islands; Rheas from South America; Kiwis from New Zealand and their extinct cousin the Moa; and the extinct  Elephant Bird of Madagascar are all ratites, members of Infraclass Palaeognathae. Most ratites are herbivores or opportunistic omnivores rather than carnivores. The lineage which these birds belong to is very different from the lineage of the Terror Birds. They are similar because of their size and because of convergent evolution – evolution enabling species to occupy an ecological niche. Two species of seriemas of South America are the only known living relatives of the Terror Birds, but they are not carnivores, but omnivores, eating plants as well as insects, lizards, snakes and smaller birds, and they are much smaller.

References:

https://en.wikipedia.org/wiki/Phorusrhacidae

Diagram of Terror Bird heights: PaleoNeolitic – Own work  ·  CC BY 4.0

Drawing of Andalgalornis by John.Conway – Own work ·  CC BY-SA 3.0

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