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Large quantities of rubies-both rough and faceted-fron~ a con~merciolly important new source in Myanmar (Buirn~n) hmve been avaiIcrble on the Bangltolt inarltet since 1992. The nzby crystrrls from the Mong Hsu marble deposit have clipymmidnl to barrel-shaped hobils and reverrl dark violet to almost black "cores" 017d red "rims." With heat treatment, which removes their blue color componer~t, the cores become intense red. The rubies grew umder varying conditions in complex growth sequences. The color distribution between cores and rims is related to a different incorporation of chrorniun~ andlor titanium during crystnl growth. Gemological, microscopic, chemical, and spectroscopic properties presented here permit the separal.ion of faceted Mong H s ~i nibies from their syntlietic and other natural counterpclrls. Problems arising hon7 artificinl fracture fillings nre also addressed.

Seventeen samples from the Malenco serpentinite in the Swiss Alps, representing systematic prograde metamorphic conditions from prehnite‐pumpellyite to upper amphibolite, are moderately to strongly magnetic (average susceptibility of 6.61×10−2 SI units) due predominantly to the presence of a magnetite‐rich spinel. Some greenschist facies samples contain the metal alloy awaruite (Ni3Fe); these contain in addition much greater amounts of magnetite. Small amounts of pyrrhotite in about half the samples complete the contributions to the total magnetization. Susceptibilities generally decrease with increasing metamorphic grade because of the production of increasing amounts of chromerich spinel which dilutes the magnetite component. These results indicate that significant magnetic anomalies should be generated in suture zones containing metamorphosed serpentinite and in areas where serpentinite is being actively subducted.