Mineral chemistry of some agates from Gurasada (Mureş Valley, Romania).

The paper presents the study of some agates from the Gurasada area (Mureş Valley, West Romania) and their igneous host rocks. Agates occur in the vesicles of strongly altered pyroclastic rocks ("banatites"), such as basaltic andesites, trachyandesites, trachytes and dacites or in the alluvial sediments along the Gurasada valley. The age of host-rocks is Late Cretaceous-Early Paleogene. Agates consist mainly of various types of α-quartz such as: chalcedony, quartzine and microquartz, associated with moganite. The genesis of agates is related with the hydrothermal solutions which altered the host-rocks. [ABSTRACT FROM AUTHOR]