"Digging For Diamonds" photo by Doug Wertman from Rogers, AR, USA
|ADDED 28 June 15: The 8.52-carat white diamond is the fifth-largest diamond found at Crater of Diamonds State Park since it opened in 1972. Found late June. Photo courtesy Crater of Diamonds State Park.|
|Nicely terminated quartz crystals. Width ~6. 5 cm. on each.|
|Water-clear quartz crystals. Width ~5.0 cm.|
As a kid growing up in rural Kansas, and being somewhat inquisitive, I was always asking some of the local “old timers” questions, lots of questions! One concerned the best sharpening stone for my pocket knife. I was informed never to use my father’s artificial carbide wheel but to acquire, perhaps from Santa Claus, a whetstone from Arkansas. I did receive such a stone, from my grandfather, and later in life as a student decided to find out more about the collecting localities of these stones. Arkansas Whetstones are composed of a material called novaculite, and more specifically quarried from a geological formation formally named the Arkansas Novaculite (Devonian to Early Mississippian in age, ~400 -~345 Ma) found in the Ouachita Mountains. Novaculite is a recrystallized (probably from low grade metamorphism) form of chert or flint (a microcrystalline quartz), and is extremely pure (~99% silica). See Blog posting 5/04/13.
|Rutile on pyrite, Mo-Ti Mine, Magnet Cover, Arkansas. Width FOV ~2.8 cm.|
|Magnetite octahedron crystal, Perovskite Hill, Magnet Cove, Arkansas. Corner to corner crystal ~1.1 cm.|
|Brookite on Smoky Quartz, Moses Hill, magnet Cove, Arkansas. Quartz crystal ~3.1 cm.|
Photomicrograph of brookite, Magnet Cove, Arkansas.. Length ~ 1.7 mm.
Photomicrograph of brookite adjacent to terminated quartz crystal. Length of brookite ~.9 mm.