
Obsidian possibly used in trephination experiments
1918-1920
1918-1920
1992-1999
1880-1920
1501-1600
1901-1930
1701-1800
1900-1992
1851-1900
circa 2016
circa 2016
circa 2016
circa 2016
circa 2016
circa 2016
1901-1930
1915-1953
1771-1830
1771-1830
1914-1918
2016
2015
1999-2001
1999-2001
1875
1771-1830
1771-1830
1701-1800
1981-1990
1998
1992-1999
1970-1985
2000
1980-1985
circa 2016
1701-1800
1900-1915
1790-1831
1601-1700
1701-1800
1750-1850
1701-1800
1950
1900-1992
1910-1937
1998
1998
1958-1960
circa 2016