
Obsidian possibly used in trephination experiments
1918-1920
1918-1920
1919
1839 (original); circa 1988 (replica)
1952-3
1917
1917
1915
1921
1934
2000-100 BCE
1920
1955; 1830
1918
1915
1922
1915
1921
1920
1917-1918
1915
circa 1920
1916
1920
circa 1920
1915
1920
1920
1915-1920
1801-1892 (prepared); 1946 (element replaced)
1918
4000-2001 BCE
circa 1920
circa 1920
1920
1915
1934
1930 (replica); 1834 (original)
1919
1916
1705-1737
1922
1920-1922
1921
1922
1917
1915-1918
circa 1919
1918-1920
circa 1915
1915-1916