In a society, where everything is made up of glass, everything would break rather easily. Things like swords and mallets couldn't function in such a world. As to still have something o work with, I thought about utilizing the sharp edges of glass for cutting, instead of slamming.

A sword, for example, would become something like an Aztec macuahuitl. Here a wooden club is equipped with several obsidian blades, creating a very effective weapon. The same basic principle should also work for other cutting tools, like axes and saws. When it comes to mining, however, things get difficult.

Striking and prying chunks out of a stone wall will simply break any glass tool, solid or otherwise. Even a glass-tipped pick will be no more useful than anything else.

So, I thought about it and came up with the concept of a chisel. Instead of striking a surface and trying to pull pieces out of it, the chisel would be placed on it and then grind itself in, creating cracks which allow for the removal of rocks.

Now my question: Would this be possible, or is the stone too hard for the glass to burrow into? does the chisel break when being hammered inside, or does its cutting edge do all the work? Also, how well would a spade work in this context? Please help me! Thanks!

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    $\begingroup$ Ordinary glass (including obsidian) is softer (or at least, it is not harder) than ordinary feldspar (which makes about 40% of the Earth's crust), so I don't think that a glass chisel would be a good tool to grind down hard stone -- the stone would grind down the chisel. Glass has a Mohs hardness between 5 and 6, feldspar between 6 and 6.5. Some stones, such as chalk, mudstone, or other sedimentary stone could maybe be ground down by a glass tool. $\endgroup$ – AlexP Apr 1 '20 at 14:18
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    $\begingroup$ If everything is made of glass, what are they mining? Why not just make better tools out of the stone they're working with? $\endgroup$ – Curiosity Apr 1 '20 at 15:03
  • $\begingroup$ They are mining gems and valuable metals such as gold and silver. They primarily use this for jewellery, and for trading with their neighboring countries. In universe they keep using the tools out of tradition, out of universe I simply think it could look really awesome. $\endgroup$ – Mat NX Apr 1 '20 at 15:49
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    $\begingroup$ What you describe seems to be a drill rather than a chisel. There's also what seems to be a logical problem, which is that if rocks exist, why do people not use them as hammers &c? $\endgroup$ – jamesqf Apr 1 '20 at 17:00
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    $\begingroup$ @MatNX a civilization that uses drastically inferior tools just out of tradition Is likely the exact kind of civilization that will not innovate. And likely won't survive contact with other civilizations for long. $\endgroup$ – John Apr 5 '20 at 18:09

How good a material is at scratching another material is measure by the Mohs scale of hardness

The Mohs scale of mineral hardness is a qualitative ordinal scale characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. Created in 1812 by German geologist and mineralogist Friedrich Mohs, it is one of several definitions of hardness in materials science, some of which are more quantitative.

Despite its lack of precision, the Mohs scale is relevant for field geologists, who use the scale to roughly identify minerals using scratch kits. The Mohs scale hardness of minerals can be commonly found in reference sheets.

Glass has a Mohs level of 5.5, fused quartz of 6-7 (this is why sand is abrasive).

Glass can only scratch materials lower on the Mohs scale, like fluorite, steel, apatite, calcite, gold.

For material harder than glass, you will simply wear down the chisel against it. Like trying to scratch a surface of steel with your nail will only wear down the nail.

The Mohs scale also explain why diamonds are used to equip bore-tips which need to drill through hard materials.

  • $\begingroup$ So, what you are saying is that, in theory, with superhard glass, on the level of diamond or sapphire, a chisel woild be possible? $\endgroup$ – Mat NX Apr 1 '20 at 15:39
  • $\begingroup$ @MatNX This answer explains one reason a glass chisel is not useful. There are other important reasons, too: It's weak in tension, it's brittle, and when it fails it tends to shatter spectacularly and with a lot of sharp edges (surely injuring the person holding the silly chisel) $\endgroup$ – user535733 Apr 1 '20 at 16:12
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    $\begingroup$ @MatNX - glass as hard as diamond or sapphire isn't glass. $\endgroup$ – jdunlop Apr 1 '20 at 17:35

First, I assume you mean 'glass' in the regular sense of window glass (aluminum silicate compounds), not in the physics sense of any amorphous non-crystaline solid. For instance, I just read up on a new palladium-metal glass that has properties comparable to steel, but I don't know if it has any of the optical qualities of window glass.

Aluminum silicate glass can be quite strong under certain contexts. For example, Prince Rupert's drops can be smashed on the head with a hammer without breaking (though any slight damage to the tail will cause them to fracture explosively). The problem with glass isn't its strength, exactly, but that it is inelastic: instead of flexing and recovering the way metals do, the amorphous structure of glass tends to develop internal fracture lines that create splits and slivers. Class that's shaped to have an edge will cut well, but any marginal force will shatter the edge, if not the entire blade.

I'm a little confused, however, about what a world that only has glass looks like. A stone chisel would be superior to glass, though it wouldn't be a great mining tool; there are no stones in this world? Most primitive cultures moved from stone tools to tools made of copper or bronze, but if there's no copper of bronze in your world, why is there aluminum (the primary component of glass)? I suppose if you topped out the periodic table at (say) 20 you could eliminate all of the heavy metals without changing the outward appearance of your world too much (you could still have dirt and rocks and life forms, all of which are mainly constructed from the lighter-weight elements), but how would your world get that way, and what would its inhabitants be moving for?

Adds some new life to that old adage about people who live in glass houses, though...


Your chisels are Prince Rupert's drops.

hammer vs Prince Rupert drop



Prince Rupert's drops (also known as Dutch or Batavian tears)1[2] are toughened glass beads created by dripping molten glass into cold water, which causes it to solidify into a tadpole-shaped droplet with a long, thin tail. These droplets are characterized internally by very high residual stresses, which give rise to counter-intuitive properties, such as the ability to withstand a blow from a hammer or a bullet on the bulbous end without breaking, while exhibiting explosive disintegration if the tail end is even slightly damaged.

Youtube contains even more strenuous tests of these amazing glass drops, including with bullets and hydraulic presses. They are glass and they can withstand hammer blows. Could they be sharpened with gradual abrasion into a chisel shape? Hmmm... Maybe! Their strength has to do with the molecular structure of the inside, not the roundness of the outside.

Be careful of the tail end.

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    $\begingroup$ A prince Rupert drop will not work as chisel The shape is part of the strength, and a sharp edge on the a drop will function just like the tail, IE the whole thing will explode as soon as it chips. $\endgroup$ – John Apr 1 '20 at 17:51

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