Obsidian possibly used in trephination experiments
1918-1920
1918-1920
1501-1600
1992-1999
circa 2016
circa 2016
1999-2001
1771-1830
1801-1900
1775-1785
1901-1930
1866-1870
1999-2001
1875
1701-1800
1880-1920
1790-1831
1901-1930
circa 2016
1998
1992-1999
circa 2016
1601-1700
1915-1953
1910-1937
1914-1918
1981-1990
1950
1601-1700
circa 2016
circa 2016
1740-1840
1851-1900
1701-1800
1771-1830
1701-1800
1701-1800
2015
1890-1910
1980-1985
1771-1830
1771-1830
1901-1999
1850-1910
circa 2016
1771-1830
1998
1914-1918
1771-1830
2016