Henry Clifton Sorby
The Sheffield scientist who invented the study of rocks in thin slices and described chondrules as frozen drops of fiery rain.
Key facts
- Born
- 1826
- Died
- 1908
- Nationality
- British
- Field
- Geologist and microscopist
Henry Clifton Sorby was born into a family of Sheffield tool makers and was wealthy enough to spend his life on research in a laboratory at his home. He never held a university post, yet he founded two whole branches of science.
Around 1850 he began grinding slices of rock until they were thin enough for light to pass through, then studying them under a microscope. This thin-section method revealed the crystals inside rocks in astonishing detail, and it is still the first thing done to every new meteorite. Sorby also polished and etched slices of steel and looked at them under reflected light, founding metallography, the science of metal structures, which transformed steel making.
In the 1860s he turned both methods on meteorites. In iron meteorites he studied the Widmanstätten pattern. In chondrites he looked closely at the chondrules and saw that many contained glass and crystals that had grown quickly from a melt. In 1877 he wrote that they looked like drops of fiery rain: droplets of molten rock that had cooled and frozen while floating free.
That description has stood the test of time. Chondrules are now known to be molten droplets that formed in the disc of gas and dust around the young Sun more than 4.5 billion years ago. How they were heated is still debated, but Sorby saw first what they were.
Did you know?
Sorby also studied the colours of plants and animals with a spectroscope and sailed his own yacht to study tides and sediments.
A thin section is ground to about 0.03 millimetres, thinner than a human hair.