Obsidian possibly used in trephination experiments
1918-1920
1918-1920
1501-1600
1992-1999
circa 2016
circa 2016
1999-2001
1866-1870
1801-1900
1775-1785
1771-1830
1901-1930
1875
1880-1920
1701-1800
1999-2001
1790-1831
1901-1930
1998
circa 2016
1992-1999
1914-1918
1601-1700
circa 2016
1910-1937
1915-1953
circa 2016
1950
1981-1990
1601-1700
1890-1910
1740-1840
circa 2016
1851-1900
1701-1800
2015
1701-1800
1771-1830
1701-1800
1850-1910
1980-1985
1771-1830
circa 2016
1771-1830
1860-1910
1998
2016
1771-1830
1771-1830