oeeuring in the Sangan arca was
fonned within two different rock groups· graitoids and
skarns. Based on the new amphibole classification and
nomenclature, the general fonnula of amphibols IS
(AB2C,T,O"OH),. Amphibole of granitoids is a
ferroedenite in which Si = 6.87 - 7.75, CaR> 1.5,
(Na+K)A > 0.5 and Ti < 0.5. Skarn amphiboles are
mostly developed within amphibole skarns and
gamet-pyroxene skarns during retrograde stage of
skarn evolution. High-temperature amphiboles are
rich in Al while low-temperature amphiboles are poor
in AI. Skarn amphiboles are classified in two groups:
(a) hastingsite in which Si = 5.99 - 6.08, CaB> 1.5,
(Na+K)A > 0.5, Ca < 0.5 and Al < Fe+] (b)
ferroactinolite in which Si = 7.61 - 7.90, CaB>1.5,
(Na+K)A < 0.5 and CaA < 0.5. Amphibole in (a) is
AI-rich while amphibole in (b) is AI-poor.