In her best-selling book, The Life-Changing Magic of Tidying Up, Marie Kondo argues that you should get rid of everything in  your life that doesn’t “spark joy”. I have accepted that I will never achieve Kondo-level simplicity, because too many things spark joy: a brass dinosaur my grandmother gave me when I was a kid, a worn penguin tibia I picked up on a beach in Uruguay, an Oklahoma rose rock, the alligator head Vicki brought me from New Orleans, an armadillo skull I found in the woods once, a sliced geode, an ammonite…the list goes on. Every area I have control over becomes, if not a cabinet of curiosities, at least a semi-organized array of curiosities.

An old box of stuff I unwrapped over the holidays. The human skull and allosaur claw are casts, all the other natural history items are real.

There are a couple of objects in my collection that give me more pleasure than any of the rest. One is a piece of shrapnel from the Sikhote-Alin meteorite – more about that another time, perhaps. The other is a 1.5″ tungsten cube.

I got the tungsten cube because of an answer on Quora to the question, “What is the most beautifully satisfying physics-based desk toy?” As the anonymous author of this particular answer wrote:

Some philistines may not consider this a proper “toy”, but I’ve had one for a year or so and am still crazy about it and have zero regret about purchasing it despite its high cost. It doesn’t do anything other than be way heavier than it seems possible for something that size to be. I think it’s mind-boggling and entertaining just to pick it up, hold it, savor its surreally strong attraction to the center of the earth, and think about gravity, matter, fundamental forces, etc.

The next time I got a nice chunk of fun money, I got the pair of 1.5″ tungsten and aluminum cubes sold by Midwest Tungsten Service. And a couple of years on, I gotta say, that purchase has probably given the best return of enjoyment per dollar of anything I’ve ever bought. For two reasons.

First, there’s the tactile enjoyment of picking up the tungsten cube. It is shockingly heavy. Pure tungsten has a specific gravity of 19.25. This cube is an alloy of 95% tungsten, 3.5% nickel, and 1.5% iron, called MT-18F by Midwest Tungsten. According to the fact sheet provided with the cube, “The addition of these alloying elements improves both the ductility and machinability of these alloys over non-alloyed tungsten, which can be brittle.” The addition of those other elements brings the cube’s density down to 18 g/cm^3. By comparison, steel is 8.05 and lead is 11.35. So even the alloyed cube still has a density more than half again that of lead. The 1.5″ cube has a mass of almost exactly 1 kg.

Even knowing, intellectually, how heavy the tungsten cube is, it’s still a kick in the brainpan every time I pick it up. It feels unreasonably, unnaturally heavy. It’s uncanny, like something out of a comic book, like it’s being pulled downward with the same force I normally associate with strong magnets.

The second reason why the cube is so great is the thoughts that it inspires. Pure tungsten has a melting point of 3422 °C (6192 °F). The W-Ni-Fe alloy, like other tungsten heavy alloys, “will begin to form a liquid phase when heated in excess of ~1450 °C (2642 °F)”, according to the Tungsten Heavy Alloy Design Manual (link). According to this page, most room fires max out at about 1200 °C, and according to this page, the temperatures of most magmas are 700-1300 °C (~1300-2400 °F). It is also extremely hard, with a Vickers hardness of 262 kgf/mm² (about 8.5 Mohs; regular steel is 4-4.5 and hardened steel is 7.5-8). The only harder substances are things like corundum; carbides of silicon, titanium, and tungsten; boron; and diamond.

So, seriously, what is going to destroy this cube? Burn down the house, and it will survive. Toss it into lava or magma, and it will sink to the bottom – even into the upper mantle – and sit comfortably, 150 °C or more below its melting point. If I owned beachfront property it would be cool to put the cube on a pebbly part of the beach and leave it there for a few years and see how – or if – it would erode. I know it can shatter if hit hard enough, but I imagine if it was just rolling around in the surf with some pebbles, the tungsten cube would wear down the pebbles and not vice versa. (It occurs to me that this could be tested with a small cube and a rock tumbler – I’ll let you know if I ever perform that experiment.)

My youngest brother, Ryan, designs drill bits for the oil industry, and then goes out to the drill sites to see how they wear down. His job is basically getting industrial diamond, tungsten carbide, and hardened steel to play well together at 1100 rpm. I wrote to get his profession opinion on the survivability of the tungsten cube.


I’m having a hard time thinking of some natural or accidental process that would destroy it. Volcano, asteroid, and A-bomb are all I’ve come up with. [This was before I’d looked up the temperature of magma.] Like, if it just got left out in the rain and the sun forever, would it corrode? Ever? How long could it be sitting there as a recognizable cube – a century, a millennium, 100,000 years?

Ryan (in an email with permission to cite):

I don’t have much experience with straight tungsten but WC [tungsten carbide] should fare better corrosion wise, it takes some pretty exotic stuff to corrode it. Now cobalt has a melting point of 2700F so if the WC got that hot the cobalt binder would melt, desintering the WC and breaking it down. However that’s way hotter than your average house fire.

Barring any natural disasters, acts of God, or man-made intervention, I would think you could set that thing on the ground somewhere and it would be just fine for a long, long time.

Fun fact #1: Pure tungsten oxidizes in air, so I imagine that’s one of the reasons they added the nickel in the MT-18F.

Fun fact #2: Ni and Co have very similar melting points. [Meaning that my W-Ni-Fe cube will desinter at about the same temp as tungsten carbide, which uses cobalt instead of nickel as the binder.]

My desk at work. Aquilops and sea otter skulls on the left are casts, the ichthyosaur is a 3D print, and everything else is real and mostly collected and prepped by me. That’s the aluminum cube in the back on the far left. The tungsten cube sits on my side of the desk, where I can play with it.

Now, I have a lot of things that I hope will outlive me, including a lot of old books and reprints. And a lot of that stuff is pretty durable, including the aforementioned meteorite chunk. But there is a big difference between holding a century-old monograph and hoping that the people who come after me will care for it, and holding the tungsten cube and knowing that it will most certainly survive for centuries or millennia, unless someone attempts to destroy it, deliberately and with a non-trivial expenditure of effort.

And that’s why I’m writing about the tungsten cube here on what is normally my fossil blog. I am surrounded by objects that represent time – developmental time for bones, geologic time for fossils and minerals, astronomical time for meteorites – but these are almost all natural products that embody the past. The tungsten cube is a human product, and in its sheer durability – and survivability – it embodies the future. It will exist in future iterations of this world that I can’t imagine. That’s a breathtaking thought.

If you’re thinking about getting a chunk of tungsten, I strongly recommend the 1.5″ cube set. A few months after picking it up, I got a 0.5″ cube of the same stuff, just to see what it would be like. It’s heavy for its size, but it’s not heavy enough to be shocking. The visceral reaction is more “huh” than “WOW!!”

It’s worth getting the set because the aluminum cube is also entertaining and it’s worth the small additional outlay (as of this writing, $133 for the 1.5″ tungsten cube alone, and $159 for the pair). The aluminum cube has a mass of 0.15 kg, exactly 15% that of the tungsten cube. I have visitors pick up the aluminum cube first. It’s funny, I guess a lot of folks haven’t had a chance to play with solid chunks of metal firsthand because they’ll pick up the aluminum cube and say, “Wow, that’s heavier than I expected.” At that point I just smile. The tungsten cube blows people away, every time. Heck, it blows me away every time, and I’ve been playing with it for two years. Highly recommended.

For a full line of cubes, spheres, and tops, check out Midwest Tungsten Service (link). Many of their products are also available on Amazon.