known as the blood of stone, what does it smell like?

The arid land began to stir as a familiar and yet nostalgic scent filled the air. Leaves swayed in the wind and wildlife scurried in search of shelter, but she welcomed it like a friend not seen for a lifetime. With the clouds hanging, the sky gave a low rumble as its promise drifted across the sky. Taking one last, thankful breath in, she walked through the door only to look back through the fly screen at her land – a land which was finally seeing rain.


CSIRO is Australia’s national science agency, responsible for countless inventions which have changed our lifestyle and advanced society. If I were to ask you what their greatest invention was, what would you choose?

Would it be WIFI, which has fulfilled our insatiable need for instant gratification? Or maybe hologram embedded polymer banknotes, which allow us to be lazier when checking our pockets before throwing clothes in the washing machine? (Did you know their first one was a $7 note prototype?!) 

Or perhaps it would be their extensive and ever growing knowledge of radio astronomy which continues to excite proud nerds like myself. Or Aeroguard, a necessity on any Australian camping trip, or family barbecue, or bush walk… or honestly anytime you want to venture into the Aussie outdoors – which was originally designed to repel mosquitos to protect Australian troops during the second world war!

These are all reasonable and commendable efforts which under any other circumstance would take the ‘top position’, however, when I consider these all next to one word they quickly become irrelevant. CSIRO gave us the word Petrichor

Petrichor is the pleasant aroma we smell when rain hits what was a parched land, and CSIRO gave us the word for it. It is derived from two greek roots, petra meaning stone and ichor which in Greek mythology is the ethereal blood of the gods – this smell was thus named the blood of the stone.

Oils from plants are excreted and land upon the earth and then adsorbed by soil and rocks so, when the rain falls this oil is released alongside Geosmin which is an organic compound produced by some actinobacteria. All of these little occurrences, culminate to the earthy aroma we define as petrichor.

Although an interesting note, is that these oils in fact hinder germination and plant growth as found in later research by Bear and Thomas. This smell which represents the hope of many farmers and Australians nationwide, ironically also limits future plant growth. 

Published in BEAR, I., THOMAS, R. Nature of Argillaceous Odour. Nature 201, 993–995 (1964).

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