7" Red, Indonesian Plume Agate Section - North Sumatra, Indonesia
This is a gorgeous, 7" wide, polished section of red, Indonesian plume agate/jasper. It was collected from Karang Jaya in Northern Sumatra. It has a deep red, coloration and many people consider the Indonesian plume agates to be some of the finest in the world. It is polished on one side and has been left rough on the opposite side. It is just under two inches thick, so it could be further worked to produce thinner slabs or cabochons.
Jasper is a term that can be applied to an opaque variety of chalcedony (light does not pass through it). The opaqueness is due to a higher concentration of impurities mixed with silica/quartz. Like agate it may form in a wide variety of colors, and is often multi-colored. In most cases, jasper will occur when silica-rich fluids permeate throughout a soft sediment or volcanic debris deposit. The fluids then crystallize around the particles/impurities, resulting in a cementation process. Most often, the impurities present determine the coloration of the deposit following solidification, however other factors can play a role in the color of what is now considered a jasper.
Agate is a variety of microcrystalline quartz (chalcedony) that displays translucence and in some cases banding. Agate primarily forms when silica-rich fluids fill pockets within rock and/or fossils, resulting in deposition of the silica along the walls of the rock. This process can result in banding patterns as the composition and impurities of the fluids change over time. These banding patterns can either form as flat layers or rounded layers, depending on the surfaces available for deposition.