The Gruithuisen Domes The Gruithuisen Domes are located on the
northeast border of Oceanus Procellarum at the highlands-mare
boundary. The three Gruithuisen domes are named for nearby
Gruithuisen crater. The two largest domes have been unofficially
referred to for many years as Gruithuisen Gamma and Gruithuisen
Delta, with the smallest dome called NW (for "northwest"). The
Gruithuisen domes are classified by lunar scientists as
"nonmare" volcanic domes. This is because we know from Earth
based telescopes, Lunar Prospector gamma-ray spectroscopy data,
and Clementine multispectral data that the domes are composed of
materials different from either the mare or highlands. The
Gruithuisen Domes are characterized by a relatively high albedo
and strong absorptions in the visible and ultraviolet, and the
domes are low in iron and titanium compared to the volcanic
deposits of the lunar mare. Previous studies of this region
showed that Gruithuisen may represent a lunar analog to
terrestrial rhyolites, dacites, or basal