Dead Man' plack is made of rock and found in Cornwall, a region of England (the capital of which is London)where Cornish is spoken.
[["Dead Man's Plack", 'LOCATION', 'England'], ['England', 'CAPITAL', 'London'], ['England', 'LANGUAGES', 'Cornish language'], ["Dead Man's Plack", 'MATERIAL', 'Rock (geology)']]