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The Stone Corner

Grin and Barite - Nov/Dec 1999

Barite is a horrible name for selling stone. It has no cachet whatever. If anything, the name has the ring of something you don't want even close. It sounds radioactive. Before now, no one has even suggested using barite as a carving stone.

 

Here is some information on a new stone for the sculptor. Barite, mined worldwide, has many industrial applications. Barium-the element derived from barite, the mineral-is used in the manufacture of glass and paint and is used as "drillers' mud" at oil rigs. It is used medically. In diagnostic enemas, doctors don't hesitate to put it memorably close to patients. Unless you drop the heavy stuff on your toe, barite is no more harmful that most any other rock. When I inquired with OSHA, I was told it could be considered benign. It is not radioactive. Too bad barite sounds like something that could light your bones green. Terrible name. There has to be something better, a trade name.

 

Barite is very seldom found pure in nature. It typically comes mixed with other minerals of varying nasty hardness and ugly colors. This explains its lack of history as a sculpting media. Different, the barite from Prince of Wales Island is virtually pure as found. A report of chemical analysis conducted for past property owners by a private metallurgical Jab describes the barite as "a finely crystalline white rock containing no visible impurities." Alaskan Barite is typically Ivory Soap white but has occasional blue-grey, lavendar, and gold tones. For so dense a mineral, it is surprisingly translucent. With a hardness similar to that of alabaster, it carves easily with hand tools. It comes from a deposit far too small and remote for commercial barium production.

 

How about calling it "Alaska Heavy Stone?" The name "barite" comes from the ancient Greek word for heavy. Its weight is perhaps its most distinguishing characteristic. Barite is 4.5 times heavier than water. By comparison, calcite, the main component of marble, is 2.7 heavier. When you place a sculpted piece of barite on the table, it wants to stay put. I used it as a ballast in my boat before I could afford pigs of lead. Because of its great relative weight, barite might make excellent base material for sculpture of other materials.

 

It has been hard to get people to try it. Janet Willing was the first to take the chance. A few unwillings have tried it, usually convinced only after great brow beating on my part. 1 asked Nicky Oberholtzer to write her appraisal.

 

Barite is a very pleasing stone to carve. It responds well to the die grinder and the angle grinder. For beginners, who are using hand tools, it is ver)' easily worked. Caution should be exercised when using chisels as the stone is fairly brittle and more may come off than you planned. For those who hate sanding and polishing, the stone is a welcome surprise because it takes less effort to sand than most and the results are immediate. It takes an incredible shine without much effort und is silky smooth to the touch by the time you have finished with 220 grit.

 

Nicky is now recommending barite to her students. But. what to call it? How about: "Alaskan Wonder Stone?" No, that one gets a finger down the throat.

 

l once had on the boat a young intern geologist with the USGS. From Texas, he identified the mineral "BAY-rite." For the rest of our trip his veteran colleagues dubbed him "the BAY-rite kid."

 

Alaskan barite comes from the tip of a penn insula that protrudes into a very open area of ocean. Like most beach cobbles (note the barnacles) the stone can only be gathered when the seas are at their calmest. The location might be accessible only thirty days a year. Typically, I anchor my bigger boat in a protected cover about a mile away and go to the barite site in my skiff. If you happen to be there at a very low tide, you can also gather abalone and rock scallops. That happened once.

 

My first two attempts to collect there this year were unsuccessful. Twice I believed a favorable weather report. Twice I was foiled by the seas-the waves pounding on the exposed beach would have pooped the skiff at the landing or swamped it at sea had I dared a heavy load. The location is seven hours by boat, one way, from my home port of Craig. A lot of time and diesel were burnt for naught.

 

"Bear-ite" might work. Think of the possibilities if I could get the native population here to use it, instead of soapstone, to carve polar bears. In spite of barite's near perfect color, all my attempts in this direction have failed. I've heard a similar story of a Canadian sculptor who failed to get Eskimos to work a beautiful white marble in their back yard.

 

I did not use the Hyak on my third attempt. A couple of fishermen, who live on a boat moored near mine, offered the hire of their backs and their boat to gather stone. Better than my boat for the chore, theirs had a large fish hold and a boom that could be used to swing aboard tone delivered by skiff from the shore. The trip took longer than expected. By the time we got to the location, the tide had already covered most of the barite on the beach. The tide was not going to be low enough again to gather stone until around mid-night. We anchored and discussed possibilities. It was either gather stone in the dark of night with a flashlight or wait until around noon the next day. They said they had to be back in town and offloaded before a pending commercial fishing opening. We set the alarm for eleven p.m. and crawled into our bunks for the couple hour wait for low tide.

 

The tide was still dropping when we got to the beach. It was necessary for one of the fishermen, wearing chest waders, to remain standing in the surf to hold the skiff-it had to be kept in water shallow enough to be loaded but also deep enough for it to not "high center" on one of the random boulders of the intertidal zone. The other fisherman and I carried barite cobbles in the dark, holding little plastic flashlights between our teeth. We carried the stones, one or several at a time, out into the water to the tops (sometimes over the tops) of our rubber boots. The man in the chest waders, splashing phosphorescence, relayed the arm loads of stone to the side of the skiff, where he placed them over the gunwale.

 

"BARITE." It's a lousy namefor a finecarving stone. but, I'll just have to accept it. Grin and barite. '"

Where to Find Stone - Nov/Dec 2000

Notes from the 6/20/00 membership meeting on the topic: “Found Stone”

 

Soapstone deposits on the road to Lake Wenatchee, WA. You must get a Forest Service permit from the Ranger Station (509 763-3103) to collect it. They can also tell you where to find the stone. The permit is about $10 and the charge for stone is about $3/cubic yard. You can drive very close to the stone deposits. The soapstone comes in many colors — light to dark chocolate, greens, golds. It has been tested for asbestos and is believed to be asbestos-free. Some Serpentine can also be found.

 

White mystery stone on the way to Lake Wenatchee, WA. Past the ranger station on the road to Lake Wenatchee look out for a quarry with snow white stone. It’s harder than alabaster. You can’t just take it, but you can talk to the folks at the quarry about its availability.

 

Marble and more, near Kettle Falls in northeastern Washington. Near the Canadian border, on the east side of the Columbia River, right near the road is an inactive quarry with marble — white with green and gold flecks. Nearby, you can also find brucite, red marble, and pink marble. While in the area look around for other inactive quarries.

 

Serpentine everywhere. There is lots of serpentine all over. Look for an outcropping 7 miles north of Olmac. Look in Kititas county, and look in the Mt. Stewart Range. Note: serpentine can have arsenic inclusions.

 

Jade by Teanaway River, about 2 hours east of Seattle area, north of Cle Elum.

 

Limestone. At Miller Quarry in Goldbar, WA. Active quarry, some carvable limestone for $0.01/pound. They also have basalt. Look for another limestone quarry on the south fork of the Skykomish River, on the way to Index, WA. The limestone is dark with light streaks.

 

Sandstone. You can find black sandstone on lots of beaches. Look for a nice, creamy-textured one in Cowichan on Vancouver Island, Canada. Tenino, WA, has a sandstone quarry also.

 

Basalt. West of Yakima, WA, by the Naches River, look for basalt columns. If you’re boating on the Columbia River, you can find lots more basalt.

 

Dumpster stone. NW Marble and Terrazzo, in Bellevue, WA, at intersection of I90 and Richards Road has scrap dimensional stone that you can take from their dumpster. Types are those used for countertops, etc. Similar stores in your area may also have scrap stone available.

 

Collecting free or almost-free stone has a price — time, energy, risk of injury, car wear, etc. For many, finding stone this way is rewarding because they feel more connected with the stone and the earth finding it in its natural setting, there is less environmental impact and the forms are natural.

 

See also the book: Gem Trails of Washington

Limestone - May/June 2009

White, creamy limestone has been a staple of Pacific Northwest sculptors since 1992 when 6 tons of Utah oolitic found its way to the Northwest Stone Sculptors 5th annual carving symposium. It owes its continued popularity (10 tons at the 1993 symposium and many more tons subsequently) to its ease of carving, low cost and wonderful finished demeanor. It is indeed a “poor man’s marble,” both genetically and artistically. With sweeping curves and shapes, limestone casts beautiful shadows and interesting lines.

 

Geology

Limestone is a rock that contains 50 percent or more calcite (calcium carbonate, CaCO3) and dolomite (magnesium calcium carbonate, MgCaCO3), of which calcite is dominant. It is the sedimentary parent of the metamorphic rock, marble. In very simple terms, it is a rock from which lime can be produced. Although it is defined chemically, the calcium carbonate can be formed in more than one way:

  • agglomeration of many smaller carbonate particles
  • chemical precipitation
  • biological growth

 

The most commonly utilized limestone is oolitic or compact limestone that is formed from marine oolites or ooliths. Ooliths are small round or oval bodies, 0.25 to 2 millimeters in diameter that form concentric circles and/or radii of calcium carbonate around a nucleus by chemical precipitation. The nucleus may be a shell fragment, a small piece of algae, or a quartz sand particle. It is important that the oolith be continuously wave or current agitated, so concentric growth can continue.

 

The ooliths eventually become heavy enough to settle to the ocean floor, accumulate in thick layers, and over geologic time, through the pressure of the overburden, form limestone that is relatively compact and uniform. Just imagine; all those oolites huddled together at the bottom of the ocean waiting to be discovered by a stone supplier. Their growth is similar to the growth process of a hail stone. Another type of precipitate is travertine, in which calcium carbonate precipitates out of a cave of spring water and forms interestingly shaped and colored rock. Among others, this is the type of rock that forms stalagmites and stalactites in caverns. This rock typically contains voids, because of the irregular way in which it is deposited. Biologically formed limestone includes tufa, which are small calcium carbonate secreting fresh-water organisms, and reef-building corals. Both of these rocks are beautiful in their natural state, but are not considered to be carving stones.

 

Limestone can be found in several colors: white, brown, red, and yellow. Although the hardness of this rock can vary from very soft (1) to the hardness of 6, the most common carving limestone is about 3 to 4. The dominant mineral is calcite, with secondary dolomite and aragonite, but there are small quantities of chalcedony, quartz and other silicates.

 

Limestone is one of the most susceptible rocks in the world to chemical weathering; for instance, consider the fact that all of the great caverns in the world are carved by Mother Nature’s groundwater from limestone. Sculptures and building stones of limestone are particularly vulnerable to degradation in areas with acid

rain.

 

Limestone has a wide variety of uses other than artistic. It is used as crushed stone for roads and embankments, a dimension stone, a fluxing agent for smelting and refining iron and other metals, a component in plaster and mortar, in the production of chemicals, an ingredient in paper and glass making, a soil conditioner, a water softener and most importantly, the prime ingredient in cement.

 

Working Limestone

Because there are so many types of limestone, it is difficult to describe the carving of all of them. The softer limestones, especially those that are biologically formed, such as tufa and coral, are not used for carving, because they are fragile and brittle. Although weak corals are not useful for carving, some beautiful metamorphosed (fossilized) corals can be carved with diamond power tools. The coral designs are spectacularly preserved in the limestone.

Travertine can be an attractive stone for sculpture with its random voids. The voids can fit into the piece or just add to the ambiance of it. The voids do cause complications in the working of the stone. It becomes very problematic to work this stone with hand tools, because chisels create spalling around the edges of the natural holes in the stone or they may open up new holes that are just below the surface. Once these holes are rendered ragged by chisel marks, they are very difficult to erase, because they are below the working surface. It is essential to work this stone with power tools, preferably grinders and burrs.

Oolitic limestone is a perfect stone for beginners and expert alike. Because of the uniform method in which it is laid down, it has uniform color and hardness. It has very few surprises; something to be prized! Although it may contain some scattered iron sulfide or quartz, it is mostly pure carbonate or dolomite. The few joints or cracks in the stone can be exploited when breaking the stone into smaller pieces. Fortunately, upon careful scrutiny, even hairline cracks can normally be spotted in oolitic limestone.

 

This limestone can be worked with hand or power tools. Roughing out the form can be accomplished with a point, and then followed with a toothed chisel to within 1/2 to 1/8 inch of the finished surface. The grooves of the toothed chisel can then be eradicated with a flat chisel. With various grades and shapes of rasps, the final touches can then be applied.  Surface smoothing can then proceed by using 200 to 400 grit wet-dry sandpaper. Paper finer than 400 grit yields very little return for the effort.

 

Texturing can be applied to oolitic limestone with wonderful results with a bushing hammer or tool and a toothed chisel. Using a carbide-tipped drill bit for a base pin hole, the limestone cuts like butter; be careful not to drill too deeply.

 

Although some limestones may be able to take the outdoors year-round, it is probably not advisable as a blanket practice. Owing to its moderate porosity; it can absorb water and suffer from freeze-thaw. A sealant is commonly applied in two coats to prevent penetration of water. As mentioned above, in the long-term, it is one of the most vulnerable of stones to acid rain attack.

 

Similar to marble, there are many reports regarding the benign dust of calcium carbonate-bearing limestone. However, don’t be too cavalier, because there are impurities, one of which is silica. So be safe and wear a mask, and keep your goggles on. You have only one pair of eyes.

Stone Queries: Quarry Sap - Jan/Feb 2009

In the book, The Agony and the Ecstasy, Michelangelo is said to have draped the David marble in damp cloth after every carving session. What was he doing?

 

While I wouldn't begin to question Michelangelo's approach, I strongly suspect that description is more artistic license of the author than artistic technique of the sculptor. Damp cloth draping is essential when modeling in clay but as far as I can determine of little or no value in marble.

 

All stone contains varying amounts of moisture, or pore water, when freshly quarried. In English-speaking countries this moisture is usually called "quarry sap" and almost always stoneworkers claim that freshly quarried stone carves more easily than stone that has dried out. Often it is further claimed that once a stone has dried out, even immersing it in water will not restore it to its original easily-carved condition. The marble block used for David was quarried, partially carved, and then abandoned for many years before Michelangelo started carving it.

 

I have carved some limestones and sandstones that soften when wetted, but these have a porosity of up to 30% and contain clay as well. Marble typically contains less than 1% moisture by weight, and many marbles from the Carrara area contain less than 0.1%. As a block of marble dries out the calcium carbonate in the pore water would precipitate along the crystal boundaries but would that be enough to affect carving or prevent later water penetration? And yet something can happen. I have seen a block of statuario marble that changed from solid stone to a sugary, crumbly mass after sitting outside a Pietrasanta studio for a year. I am still looking for any scientific studies that confirm the lore or document precisely the physical and chemical changes occurring with loss of pore water that would affect carving.

 

I have been warned to avoid unscrupulous stone dealers selling old dry blocks to sculptors who don't know any better. But how quickly does a block dry out? Not many of us have the luxury of plucking a block from the quarry face as soon as it's extracted, so I have stopped worrying about stone freshness.

 

So what was Michelangelo doing? Was he even doing it? The only contemporary reference I have been able to check so far is Vasari's "The lives of the artists" and he does not mention damp cloth draping. Or did Michelangelo know something about stone that I don't? You bet he did! But was this it?

Stone Queries: Soapstone - July/Aug 2008

Soapstone has become universally used as a carving medium by beginners and experienced journeymen alike, as well as those sculptors who appreciate its ease of working and its brilliant finish. It can be rapidly worked in detail with hand or power tools and can be brightly polished in beautiful hues. In its natural condition, it is earthy and mundane; one wonders why some sculptor first started to work this stone.

 

Geology

The geologic term for soapstone is talc or steatite; the two terms are synonymous. Talc is the name that you will find in a book of minerals; however, steatite will commonly be listed in the description. Reportedly, the term steatite was used commonly during World War II to describe massive and machinable talc that could be turned into strategic products such as insulators and metal molds. There are many grades of soapstone, ranging from hard to soft and dense to flaky. Soapstone has a minimum of 20 % talc, but can contain several subordinate minerals.

 

Talc is the indicator mineral for a hardness of 1 on the Mohs Hardness Scale. This mineral has a greasy feel, and is a very poor conductor of electricity and heat, the reason it is used as an insulator.

 

Minerals that commonly are found in association with soapstone are chlorite, serpentine, magnesite, antigorite, pyrite and enstatite. Another mineral that is similar and can only be distinguished from talc by chemical or x-ray analysis is pyrophyllite, hydrous aluminum silicate.

 

Talc can be formed in two ways. It is the product of alteration of other rocks and minerals; or it has been metamorphosed. It can be regionally altered dolomitic limestone or altered igneous rocks. Therefore, talc is commonly found in two different environments: massive deposits or veins. The alteration from the original rock, such as olivine, to talc is made in a water-rich environment at moderate temperatures of about 1300 degrees F. Commonly, the vehicles for the intrusion of water are shear zones along faults.

 

While the formation of talc is not a direct result of the movement, the travel of water along the zone of weakness completes the process. The largest bodies of soapstone come from regional metamorphism (burial) of large deposits of dolomitic limestone, a calcium magnesium carbonate.

 

Some of the larger bodies of soapstone in the world are located in Ontario Province, New York, North Carolina, Georgia, California, Austria, Madras and Italy. The smaller bodies tend to be narrow veins related to shear zones or igneous intrusions, and are commonly found in Washington, Virginia and California.

 

Colors vary considerably: buff, brown, gold, red, orange, black, green, blue, and black with white marbling. Frequently, the outside of the rock may be red and this iron-oxide weathered zone will give way to another color on the interior of the stone. In the Pacific Northwest, the most common colors tend to be buff, brown and green.

 

Quarrying

Soapstone is obtained in several ways, depending on the size and accessibility of the deposit. One method with which many of those in the Northwest Stone Sculptors Association are familiar, is hunting for cobbles and boulders on the slopes of a landslide deposit near Lake Wenatchee. (A commercial mining company now formally claims this deposit, so it is no longer open to us, but as of Oct. 2000, one of our members found another deposit, which is not on that claim.) The soapstone chunks are scattered about the landscape, and a shovel and crowbar are necessary tools to liberate them. Sometimes small pieces can be found that are the right size to just toss in the back of the truck, whereas other larger behemoths must be cut in place with a bow or chain saw to gain a manageable piece. Some of the larger boulders have soapstone on the outside, but then transition to another harder rock type on the interior.

 

In vein deposits, a backhoe is commonly used to loosen soapstone chunks, following the line of the vein. In the massive deposits or in very wide layers, the materials can be worked with a dozer and a backhoe together. It is common for the quarry operators to use the natural joints and weak planes in the formation to loosen the rock. Each piece is then trimmed into sizes ranging from 5 to 1,000 pounds, using chain, band and bow saws. The waste materials from larger quarrying operations can be used for such things as cooking stones or foot warmers, and as additives in paint and cosmetics.

 

The Asbestos Quandary

Is there asbestos in the soapstone that we chip and pulverize right in front of our faces? The answer is yes and no. Asbestiform laths are obvious in some of the soapstone that we see; however, the asbestos particles do not have to be visible to the naked eye or even magnifying glass to be harmful. It has been reported that roughly 40 to 50 percent of the soapstone contains some asbestos. The only way to know for sure is to have the stone tested by a laboratory. Soapstone from the Lake Wenatchee area and Marblemount tested clean this year. However, one stone does not a quarry make; different parts of a quarry can contain different accessory minerals. To be on the safe side, if you are not going to test each piece of stone that you work, treat the stone as if it does contain asbestos and wear appropriate breathing protection.

 

Tools and Flaws

Soapstone can be worked with both hand and power tools. The watchwords should probably be, "Don't break the tea cup with a sledge hammer." Tools used on soapstone should be appropriately suited and sized to this very soft rock. The use of a large hammer or chisel can cause the unwanted splitting of the rock along an unnoticed plane of weakness. It is preferable to be on the safe side by using smaller hand tools. Because soapstone can usually be removed readily with rasps and rifflers, they should be used in the vicinity of a linear flaw.

 

Rasps, rifflers and then sandpaper are the orderly progression for the smoothing and polishing process. Water should be liberally used during the sanding to aid in the polishing and to keep the pores of the wet/dry sandpaper unclogged.

 

It is common for there to be harder spots in the stone and even small pieces of iron pyrite. That will put a dent in your rasp! On the other hand, there are reports of finding small voids in soapstone, perhaps from the weathering of sulfides.

 

An interesting development was reported in a 1992 edition of Sculpture NorthWest by Patty McPhee regarding the firing of finished soapstone pieces to cone 4

(about 1,600 degrees F). She reported that this process turned the soapstone pieces very hard and darkened them. The firing increased the hardness from 1 to about 4 or 5. This could be a welcomed development to soapstone sculptors, but it is still experimental, as others have reported that the firing of soapstone has caused the destruction of a finished piece.

 

Appreciations

Thanks to sculptor Rich Baker of Ellensburg, Washington and to quarry operators John and Steve Pugh of Steatite of Southern Oregon, Inc. in Grants Pass, Oregon for sharing their knowledge and expertise of soapstone.