Active stratovolcano (trachyandesite to trachyte) on the margin of the Ross Sea.
Present activity is fumarolic.
Trachyte from the northern side of Mt Melbourne is garnet-bearing.
Garnet is intergrown with groundmass feldspar, producing an oikocrystic texture.
The formation of garnet result from localized gas-streaming in
the lava, reacting Ca-rich residual melt according to the reaction: augite + magnetite + glass + O2 = andradite (above 700 °C).
Ref. Goldschmidt Conference Abstracts 2005
Environmental Geochemistry/Mineralogy
http://www.the-conference.com/2005/gold2005/web_pdfs/G07.pdf
