Galena node

Entries

1. Entry 1

   Early twentieth-century crystal radio sets used galena crystals as semiconductor detectors, with a thin "cat's whisker" wire rectifying incoming radio waves into audible signals.

2. Entry 2

   Ancient Egyptians ground galena into the black eye cosmetic kohl, worn by all social classes for beauty, sun protection, and religious significance since at least the predynastic Badarian period.

3. Entry 3

   Galena is a natural semiconductor with a band gap of about 0.4 eV. Early 1900s crystal radio sets used galena crystals as point-contact diode detectors, making it one of humanity's first semiconductor devices.

Tasks that unlock the entries