Wednesday, October 6, 2010

Drilling with Nephrite

Reproduction drill bit and drilled slate
Nephrite is another name for Jade, a typically green stone known for its toughness.  It shows up in Palaeoeskimo, Thule, and Inuit archaeological sites in Newfoundland and Labrador.  The Palaeoeskimo ground and polished it into cutting and carving tools.  The Thule used it for endblades and drill bits.  All of the nephrite drill bit artifacts shown in this post come from Thule or Inuit sites in the Province.

Thule Nephrite drills at The Rooms
I find nephrite a difficult stone to work, especially for making things like knives and endblades that have a thin edge.  Its brutally hard to grind and as it gets thinner it can break apart in big kernels, kind of like styrofoam breaking apart.  Thicker tools like Burin-like tools and drill bits aren't so bad.  Nephrite drill bits typically have a cylindrical drill end with a bevelled point and a squarish or rectangular hafting end for mounting into a wooden shaft. (In the photo on the left, I use the bit that is the second from the bottom as the model for the bits that I make and use in my workshop.)

A long drill bit from Okak, Labrador
The bit end of the Okak drill bit
By the time the Palaeoeskimos came to Newfoundland and Labrador they'd stopped using drills - all of the holes that they made in their tools were gouged, so they tend to be long and narrow.  The Thule, on the other hand, drill holes in everything.  That's one of the first tricks that I learned when making Arctic reproductions - if you want something to look Thule, then drill a bunch of holes in it. The bow drill is such a surprisingly quick and efficient tool that its actually quite easy to make neat, cylindrical holes in wood, antler, bone, slate, and soapstone.

My workshop bow drill
I especially like using the bow drill with a nephrite bit on ground slate tools.  Holes drilled through stone tended to be drilled from both faces and meet in the middle at a slight bevel.  The holes are slightly narrower in the middle, so they have an hourglass shaped cross section.  Using a bow drill to drill the holes in the traditional way makes the reproduction a little more accurate and, in all honesty, it is quicker and less prone to chattering on the stone surface than using an electric drill.  The drills that I use in my work are the same ones that I use at ground stone workshops. You can see one being used in a video clip in this earlier post from the Ground Stone Family Fun Day at The Rooms.
My nephrite drills and the bevelled holes that they make in slate

Photo Credits: Tim Rast


  1. Did you use an abrasive, or was the grinding done by the nephrite itself?

    I'm really amazed by how neat the holes in the slate are. You've effectively got countersunk holes, which opens up all sorts of decorative and practical possibilities

  2. Yeah, the shape of the holes work very well with laces, there's no real sharp angles to cause wear.

    I don't use any abrasive, although sometimes I'll use a bit of water to keep the dust down and to cool things off. The same device (with bitless wooden spindles) was used to start fires, so the temperatures can build up quickly.

  3. Can you use a small amount of water so that the dust doesn't wash away? It's presumably a very fine powder, so would an oil work to lubricate the hole and collect the powder - I'm asking this because I'm interested abrasives and how finely they can be ground with primitive tools.

  4. The water is optional. It would be very easy to collect the dust. When you drill, a little pile of slate dust forms around the bit, like a tiny termite mound. I usually just blow it away when the pile obstructs my view, but you could tap it into a small container and save it. If you add a few drops of water that dust turns to a clayey-mud. I'm sure oil would grab it, too.
    I haven't really considered other uses for the slate dust. Although, I have collected soapstone dust like that in the past to mix with epoxy on repairs or to create artifical patinas on reproductions. You can get a lot of dust quickly by just starting to drill a few holes. Soapstone dust would probably be more of a lubricant than an abrasive though. Like talcum powder.

  5. Before the advent of electricity, it's surprising how many minerals were used as abrasives - the surfaces of gold and silver are very easily scratch, particularly if the surface was enriched (higher gold/silver content), or if they were using pure metals instead of alloys.

    Even in our lifetime, jewellers were using charcoal for fine finishing work - the softness of some of the mineral powders is quite important to that.

  6. The whole "drill holes in everything" is definitely an eastern addition to Thule. Early Thule in the west had drills (mostly chert, at least around Barrow) and bow drills, but they used them to make holes where they needed a hole. The idea of cutting something in half by drilling a bunch of holes & snapping the intervening material just doesn't seem to have been popular, nor did it become so later. People grooved & snapped, not drilled & snapped.

  7. Ajatnuvuk, that's really interesting. I didn't realize before this that there was such a big difference in drill use between the Eastern Arctic and the West. But I should have guessed it -- Lori is always trying to convince me that folks on the west coast are groovier than folks in the east.

    Its interesting about the chert drills around Barrow. Chert drills are what I was accustomed to on the Plains, and I've kept my eyes open for them in the Newfoundland and Labrador collections, but I can't remember ever seeing a single one. There might be a few chert "borers" that have a bit of a beak on them, but nothing that would have been mounted on a spindle. None of the NL cultures seem to have had chert drills.

  8. I have them on my website at


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