Q 01/05

Which volcano's 1883 explosion left pumice rafts adrift, tree trunks and all, for up to 20 years?

A) Tambora

B) Krakatoa

C) Mount Pelée

D) Mount Etna

Answer · why

B) Krakatoa

Krakatoa threw out so much pumice that in places the floating raft stood 1.5 metres above the waves. Ships reported huge fields of it for months after...

Q 02/05

Which Roman landmark did engineers lighten by adding more pumice to the concrete as they built higher?

A) Colosseum

B) Trajan's Column

C) Pantheon

D) Arch of Titus

Answer · why

C) Pantheon

The Pantheon's dome is still the world's largest unreinforced concrete dome, almost 2,000 years on. Light pumice and tufa at the very top keep its wei...

Q 03/05

Which clothing gets its faded, worn-in look from being tumbled with pumice stones in a rotating drum?

A) Denim jeans

B) Leather jackets

C) Wool sweaters

D) Silk scarves

Answer · why

A) Denim jeans

Denim jeans are stone-washed with pumice, which also softens the stiff cloth. The catch is that each pair wears out sooner.

Q 04/05

Which soft-furred pet rodent keeps clean by rolling in a bath of fine pumice dust a few times a week?

A) Guinea pig

B) Hamster

C) Gerbil

D) Chinchilla

Answer · why

D) Chinchilla

A chinchilla should not bathe in water, because its fur can mat and grow mould. The animals take to their pumice dust baths by instinct.

Q 05/05

Pumice was once called spuma maris in Latin because people believed it was hardened what?

A) Sea salt

B) Whale bone

C) Sea foam

D) Coral sand

Answer · why

C) Sea foam

Sea foam seemed a fair guess for a pale stone found bobbing on the waves. Around 80 BC the Romans also knew it as lapis spongiae, for its sponge-like ...