# @stem_antics on Instagram

- **Type:** Video
- **Original URL:** https://www.instagram.com/p/DdT74EYAsWb
- **Gondola URL:** https://gondola.cc/posts/70577848-stem-antics-instagram
- **Thumbnail:** https://img.gondola.cc/tr:w-,h-,fo-auto/postThumbnails/c80f79cc9e.jpg
- **Posted:** 2026-09-15T14:36:13.000+00:00
- **Account Owner:** Stem Antics (@stem_antics) — https://gondola.cc/stem_antics

## Caption

Rock does not yield to force. It yields to something harder than itself, turning fast enough to grind quartz into flour. That is the entire premise of diamond drilling, and it is why almost everything we know about the crust beneath us arrived at the surface inside a hollow tube.

A core bit is annular. It cuts a ring rather than a disc, leaving an intact cylinder of rock standing in the middle, which is captured in an inner barrel and lifted out. Rodolphe Leschot patented the idea in 1863 while tunnelling through the Alps, setting carbonado, natural black diamond, into the crown of a rotating pipe. The geometry has barely changed since.

What changed was the diamond itself. Tracy Hall and the General Electric team synthesised the first reproducible stones in December 1954 at roughly 10 GPa and 1600 degrees Celsius, and abrasive grit became an industrial commodity rather than a Brazilian import.

Modern impregnated bits are built around that grit:

- Synthetic diamond is dispersed throughout a tungsten carbide matrix and hot pressed into a crown
- The matrix is engineered to erode at a controlled rate, continually exposing fresh cutting points
- Soft matrix for hard rock, hard matrix for abrasive rock; a mismatch either polishes the crown glassy smooth or strips the diamonds out before they have done any work

Diamond conducts heat better than any other known material, near 2000 watts per metre kelvin, which matters enormously because it graphitises above roughly 700 degrees Celsius. Flushing fluid removes cuttings and heat in the same stroke. Starve the face of water for half a minute and the bit destroys itself.

The core is the product. Assay grades, fracture orientation, rock quality designation: none of it survives being crushed into chips.

Hardness is worthless without something to carry the heat away.

#stemantics #geology #drilling #materialsscience #engineering

## Stats

- **Views:** 24,540
- **Likes:** 210
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- **Comments:** 3

## Tags

engineering, materialsscience, geology, drilling, stemantics

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