AFRICAN MINERALS Minerals, Gemstones And Jewelry Information FEBRUARY 2, 2017 What Are Quartz var. Chalcedony Dusted With Pyrite? joanne BLOG Quartz crystals from the 2nd generation occur in a number of different habits including individual multiple growth crystals, clusters of radiating multiple growth crystals or flower quartz and thick seams or crusts of drusy multiple growth crystals. In general, crystals from this generation are vitreous but internally clouded. The most aesthetic examples from this generation are individuals and clusters resting on second generation ferroan dolomite. An example of a multiple growth flower quartz cluster is displayed in the photo to the upper right. The 2nd picture to the right exhibits a classic specimen of 2nd generation quartz crystals sprinkled on second generation ferroan dolomite. Most quartz crystals from this generation typically have moderately to severely etched prism faces. This is generally more pronounced in larger crystals. Smaller crystals will typically have a series of etched, graphic markings on the prism faces perpendicular to the terminations of the crystal. The photo to the upper left displays a smaller crystal with these markings. An X-shape is often formed on the prism faces of crystals from this generation, because of the parallel multiple growth habit. In some smaller crystals, this X-shape is reduced to a set of notches on the prism face as seen in the photo to the upper left. In larger crystals from this generation, the etched markings are heavier through the center of the prism faces, as seen in the second photo to the left. The multiple terminations of larger crystals tend to angle slightly from the center of the crystal amplifying the X-shape of the prism faces. In extreme cases, the terminations of the crystal appear to be two separate crystals, grown in parallel and terminated into one another. On these crystals the X-shape is expanded into an hourglass shape. An example of this is pictured to the lower left. The prism faces are commonly highly etched on these crystals. Although isolated crystals from this generation are generally less than 2 cm in size, larger crystals are often found in thicker seams. When these seams open into pockets, crystal points alone up to 2 cm across have been observed. Specimens of drusy quartz are generally more clouded than individual crystals. This is more likely due to the larger size of the crystals, than the habit. A typical example of drusy quartz from the 2nd generation is pictured to the lower right. This habit is one of the more common and least desirable occurrences of quartz at the Monroeville locality because the crystals are less distinct. A Guide to Iolite About Us My name is Paul and I had been a gemologist for over 15 years. African Minerals is a blog I share my thoughts about the jewelry industry and articles that I come across in my travels. To reach me, email me at paul@african-minerals.com Our Partners Recent Posts Lab Grown Diamonds – What Are They and Where Can I Buy Them? A Guide to Sunstone Should I Worry About Feather Inclusions? A Guide to Iolite What Are Quartz var. Chalcedony Dusted With Pyrite? Other Useful Links Crystal Lattice Structures Gems, Rocks and Minerals Mineral Collecting Beyond the 4Cs The Mineralogical Record Documentary Video Player 00:00 52:01 © African Minerals 2018 Powered by WordPress • Themify WordPress Themes