These, mercifully, have grown much rarer in Egypt in recent years.
This may, in part, be because large spills have grown rarer as tanker technology, too, has improved.
It must be said that successful partnerships are rather rarer than failed ones: Business people tend to be alpha types, and money and fame can destroy even the solidest friendships.
Volcanoes that change climate enough to affect agriculture round the world are perhaps 100 times rarer than that, and cataclysmic asteroids rarer still.
It is rare that a banker admits to the inevitability of onerous new rules and it is rarer still for a Rothschild rainmaker to speak out.
But in fact, violent crime is far rarer in Japan than elsewhere.
Antipathy towards Mormons is rarer among well-educated Americans (64% of college graduates have a favourable view of them) and among people who actually know a Mormon.
Some species of snail have shells that spiral out in an anticlockwise direction, but it is much rarer.
As well as going after dolphins, villagers not allowed to hunt the minke whales along the coast have turned to hunting (rarer) toothed whales not covered by the IWC's moratorium.
The higher you climb up the mountain, the rarer the air is.
