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Silicified coral specimens taken from the Barisan Mountains (Sumatra, Indonesia) have been studied by Hyperspectral Raman and Cathodoluminescence (CL) Spectroscopy coupled to Environmental Scanning Electron Microscope (ESEM-CL) with an energy dispersive spectroscopy probe (EDS). Three different parts were recognized in the silicified coral: i) the external shell, radial (septa) and inner circular walls, and also the core central part of the coral are build up of opal with some disperse carbon-rich black grains, showing the G and D Raman bands from residual organic matter; ii) the inner caverns are stuffed with megaquartz crystals of high crystallinity; iii) chalcedony fibers occurring among both described zones, including moganite mineral phase identified by its 502 cm-1 Raman band. All regions display spectral CL bands at 295, 325, 370, 395, 430, 450, 485, 605 and 655 nm being maxima these last emission peaks. The monochromatic CL mapping at 605 nm shows intense CL emission from the rim septa. Septa are made of cryptocrystalline silica phases neo-formed by volcanic-hydrothermal mechanisms since the broad band centered at 560–580 nm is related to oxygen vacancies in natural hydrothermal quartz and the orange to red emission band circa 620–650 nm has been detected in almost all natural hydrothermal quartz being explained by recombination of electrons in the non-bridging oxygen band-gap state with holes in their valence-band edge. Accordingly, these associated defects to the longer wavelength emission peaks suggest a possible hydrothermal origin for the quartz. The presence of AgS and Zn-Cu minerals inside the coral fissures also indicates a probable hydrothermal source for the silica linked with the local volcanic activity. [ABSTRACT FROM AUTHOR]