As good as glass
These mica sheets were found at Woolwich dockyard. Mica is a shiny transparent mineral, which was imported by the English Navy from Russia. It is known as 'Muscovy glass' or muscovite after the Russian province of Muscovy. It could be split into sheets, making it very suitable for glazing.
What was the mica for?
These mica fragments date from 1680-1720. The Navy would have used them to glaze cabin windows or the 2.5-metre-high poop deck lanterns on board ships. Several of these mica sheets have been cut into diamond-shaped panes. In the early 18th century, the Navy began to use glass instead, by order of the Admiralty.
Woolwich was one of the royal dockyards along the Thames. The dockyard was used for building and repairing ships. Being close to London, it was easy to get supplies and workmen.
Museum number 80.271/44a-k