7.6" Polished Brazilian Agate Slab with Amethyst

This is a gorgeous, 7.6" wide polished Brazilian agate slab. It features colorful banded agate and an amethyst crystal lined pocket at its center. Comes with an acrylic display stand.

Agate is a translucent variety of microcrystalline quartz. 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.

Agate has also been known to fill veins or cracks in volcanic rock. Such agates, when cut transversely, exhibit a succession of parallel line giving a banded appearance to the section. Such stones are known as banded agate, riband agate and striped agate.

The agates from Brazil are mined from decomposed volcanic ash and basalt from the late Permian age (248-275 million years old) In Rio Grande do Sul the "agate mines" are normally just plowed fields in which loose agates are found and collected. These agates can be very colorful and polish beautifully.

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.

Silicon Dioxide, also known as SiO2 or Quartz, is the second most abundant mineral in the Earth's crust. Quartz crystals generally grow in silica-rich, hot watery solutions called hydrothermal environments, at temperatures between 100°C and 450°C, and usually under very high pressure. Quartz veins are formed when open fissures are filled with hot water during the closing stages of mountains forming, and can be hundreds of millions of years old.

Amethyst is a purple variety of quartz (SiO2) and owes its violet color to natural irradiation, iron impurities, and the presence of trace elements, which result in complex crystal lattice substitutions. It’s considered a semi-precious gemstone, and just two centuries ago was considered to have a value on par with diamonds, sapphires and rubies. The largest and best known amethyst deposits occur in southern Brazil and Uruguay but many localities around the world produce an amazing variety of amethyst crystals and formations.
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DETAILS
SPECIES
Quartz var. Chalcedony & Quartz var. Amethyst
LOCATION
Rio Grande do Sul, Brazil
SIZE
7.6 x 3.7", .7" thick
CATEGORY
SUB CATEGORY
ITEM
#145501