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