Once infused with silica, the differences between the mineral’s properties become extremely minor. Rhyolite can end up with a higher silica content over time as the beds get altered due to geological processes. Because of that, it’s often softer than jaspers at a 6 instead of a 7 on the Moh’s scale. Rhyolite’s main difference lies in the fact that a good bit of the material is feldspar. Pinning down “jasper” gets painful in a hurry once we move out of geology, however, as some of the most common varieties of jasper could be considered other stones. Jasper, on the other hand, is… an opaque aggregate of chalcedony and other crystal phases of silica. The difference is in cooling: rhyolite cools more slowly which allows for crystal formation to begin as opposed to the amorphous glass of obsidian. It’s a common feature in volcanic eruptions, essentially made up of the same minerals as obsidian. Rhyolite is a silica-heavy mineral, often colored red by iron contamination. It’s similar to granite in composition, hard and taking a great polish. Here’s the skinny of it: rhyolite is an intrusive igneous stone and among the most common in the world. There’s a lot of argument surrounding the various jasper and rhyolite qualities in certain rockhound circles. The spheres are comprised of an initial crystal seed which then shows radial growth, making them appear as spots when the stone is cut. Think Grape Agate contained within a stone. The tiny spots on the exterior of a polished stone are actually the remnants of an internal crystal structure. It’s one of the stones I’ve frequently found in bags of mixed polished stones for… over 20 years now. It’s pretty, takes a high polish, and it occurs in large formations that allow it to be used for carvings in addition to the normal jeweler’s use. The stone itself is pretty common in the trade. The actual difference for a collector or lapidary artist between these variety of stones is non-existent. We’ll discuss this in a moment, but on a technical basis, Leopard Jasper is actually silicified rhyolite. The latter is very close to Oolitic Jasper, but they have a different proposed formation type. Its patterns are similar to other jasper-type stones, notably Ocean Jasper and Orbicular Jasper. These stones generally have a lighter-colored background, with “spots” that are outlined in black. It’s also called Leopard Stone and Leopard Spot Jasper, it’s all the same thing. Leopard Jasper is a cryptocrystalline silica variety that’s opaque and has patterns that resemble a leopard’s spots. Its unique coloration patterns and ability to take a great polish make it a favorite for collectors and more than one piece has found its way into jewelry made to show off its spots.īut what is it and where is it from? Read on, as I take you on a deeper look. There are an innumerable variety of different jaspers out there, but Leopard Jasper remains a favorite.
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