Macusanite, originally believed to be a type of tektite because of its sculpture, is shown to be related to sillar of the Macusani region, Peru. K-Ar measurements establish identical Pliocene ages (4.2 m.y.) for macusanite and sillar and relate these deposits to the extensive ash flows of the southern Andes. These rocks are unique for glassy rocks in that lithium, boron, and arsenic contents are very high; cesium, rubidium, tellurium, fluorine, and tin are higher than normal; zinc, copper, chromium, and zirconium are lower than normal; and high-alumina minerals such as andalusite are present.
|Title||Macusanite occurrence, age, and composition, Macusani, Peru|
|Authors||Virgil E. Barnes, George Edwards, W. A. McLaughlin, Irving Friedman, Oiva Joensuu|
|Publication Subtype||Journal Article|
|Series Title||Bulletin of the Geological Society of America|
|Record Source||USGS Publications Warehouse|