Editing Group 7 element (section)

=== Manganese ===
Manganese dioxide, which is abundant in nature, has long been used as a pigment. The cave paintings in [[Gargas, Haute-Garonne|Gargas]] that are 30,000 to 24,000 years old are made from the mineral form of MnO<sub>2</sub> pigments.<ref>{{cite journal|doi=10.1007/s00339-006-3510-7|title=Minerals discovered in paleolithic black pigments by transmission electron microscopy and micro-X-ray absorption near-edge structure|date=2006|last1=Chalmin|first1=E.|last2=Vignaud|first2=C. |last3=Salomon|first3=H.|last4=Farges|first4=F.|last5=Susini|first5=J. |last6= Menu|first6=M.|journal=Applied Physics A|volume=83 |pages=213–218|issue=12|bibcode=2006ApPhA..83..213C|hdl=2268/67458|s2cid=9221234|url=http://orbi.ulg.ac.be/bitstream/2268/67458/1/fulltext.pdf}}</ref> Manganese compounds were used by Egyptian and Roman glassmakers, either to add to, or remove, color from glass.<ref>{{cite journal |doi=10.1126/science.133.3467.1824|date=1961|last=Sayre|first=E. V.|author2=Smith, R. W.|title=Compositional Categories of Ancient Glass |volume=133|issue=3467|pages=1824–1826|journal=Science|pmid=17818999|bibcode=1961Sci...133.1824S|s2cid=25198686}}</ref> Use as "glassmakers soap" continued through the [[Middle Ages]] until modern times and is evident in 14th-century glass from [[Venice]].<ref name="ItGlass">{{cite journal |doi=10.1007/s11837-998-0024-0|title=Glassmaking in renaissance Italy: The innovation of venetian cristallo|date=1998|last=Mccray |first=W. Patrick|journal=JOM|volume=50|pages=14–19|issue=5|bibcode=1998JOM....50e..14M|s2cid=111314824}}</ref>