An outbreak of norovirus has cast a shadow over the holiday plans of passengers aboard Holland America Line’s Rotterdam.

More than 100 people got sick in a norovirus outbreak on a Princess Cruises ship. Among 3,001 passengers aboard the cruise ...

Gem and mineral hardness is measured on the Mohs scale. The numbers are based on the relative ease or difficulty with which one mineral can be scratched by another. But the Mohs scale is deceptive.