
Obsidian possibly used in trephination experiments
1918-1920
1918-1920
1999-2001
1501-1600
1901-1930
1970-1985
1701-1800
1900-1992
1701-1800
1880-1920
1981-1990
1900-1915
1998
1992-1999
2000
1851-1900
1980-1985
1901-1930
1915-1953
1701-1800
1771-1830
1771-1830
1914-1918
2016
2015
1999-2001
1875
1771-1830
1771-1830
circa 2016
circa 2016
circa 2016
circa 2016
circa 2016
circa 2016
circa 2016
1790-1831
1601-1700
1701-1800
1775-1785
1750-1850
1701-1800
1910-1937
1998
1998
1992-1999
1958-1960
1601-1700
1970-1985
1871-1930