Glass knife

In modern electron microscopy glass knives are used to make the ultrathin sections needed for imaging.

The same technique was used to make tools, including knives, out of obsidian, natural volcanic glass.

[4] Modern glass knives were once the blade of choice for the ultra-thin sectioning required in transmission electron microscopy because they can be manufactured by hand and are sharper than softer metal blades because the crystalline structure of metals makes it impossible to obtain a continuous sharp edge.

A common practice is to use a glass knife to cut the block which contains the sample to near the location of the specimen to be examined.

[citation needed] Obsidian, a naturally occurring volcanic glass, is used to make extremely sharp surgical scalpels, significantly sharper than is possible with steel.