Quartz—The timeless mineral
By Margi Jenks
“Would you like to see my rock collection?” Over my 25 year career as a geologist I have often been asked this question at the end of dinner at a friend’s house. And, of course, I really enjoy looking at rock collections, so I always say “yes”. However, the experience is often awkward for me, because 8 out of 10 of the rocks in the collection will be some form of quartz. I find myself saying “that’s quartz” over and over again, and my friends grow tired of the repetition. So, why is this true?
Well, four quartz characteristics make it such an attractive rock to collect. First, it is the second most abundant mineral on the Earth’s surface. So, lots of it are found in riverbeds and beaches, where we generally pick up pretty rocks. Second, due to its crystal structure, quartz can take on a lovely rounded appearance. When a piece of quartz is in a stream or the ocean the moving water knocks the rock pieces together. That process gradually chips off the rough edges and slowly rounds the outside surfaces. Third, quartz easily takes other minerals, especially iron, into its crystal structure, so quartz pebbles come in a variety of pretty colors. Finally, quartz, unlike other minerals, does not break down or weather chemically and turn into some form of clay. So, it lasts and lasts in most environments. Only breaking quartz into smaller and smaller pieces will ever turn it into clay. Those white sandy beaches in Florida—they are made out of very fine sand-size grains of quartz. The red sands of the Australian outback—they are the final product of millennia of weathering that has turned all of the other minerals to clay, and washed them away, leaving behind the red quartz sands.
Here at the Crater, most of our non-diamond collectible rocks are made out of quartz—the rounded jasper that is everywhere on the search field, the amethyst that visitors sometimes find, the little quartz crystals, and the agate that makes such beautiful jewelry. The gem forms of quartz are citrine (yellow), amethyst (purple or green), and rose quartz. But, we make jewelry out of a number of other quartz rocks—chalcedony, tiger’s eye, onyx, smoky quartz, and carnelian, to name a few.
Probably half of the rocks and crystals that our visitors turn in as possible diamonds are either quartz crystals or jasper, an opaque rounded stone. We use four quartz crystal characteristics to tell them from diamonds. First, they do not have a “diamond shine”, they have a glassy shine. If you put a quartz crystal and a rough diamond next to each other, the rough diamond will always win the shine contest, hands down. Second, most of the quartz crystals have sharp edges or pointy parts. Most of our diamonds are rounded, unless they have been broken. Third, quartz crystals almost always have specs of dirt sticking to them. Diamonds have no static electric charge, so dirt does not stick to them. Finally, if you look carefully at the flat facet of a quartz crystal, you can generally see fine lines running across the facets. Those ladder-looking lines result from the way the quartz crystals grow, and diamonds don’t have those lines.
But, if you do find a pretty little quartz crystal here, don’t feel bad. After all, it is the closest in characteristics to a diamond of any of the minerals found on the diamond search field. So, you are definitely on the right track.
Search area last plowed: February 23, 2011; Most recent significant rain: March 4, 2011
Total diamonds found in 2011: 57
Diamonds registered for February 26 – March 5, 2011 (100 points = 1carat):
February 26 – David Reach, Conway, AR, 38 pt. yellow; Lee and Traci Putnam, Houston, TX, 10 pt. white; Kenny and Melissa Oliver, Rosston, AR, 22 pt. white; Michele White, Sherrod, AR, 1.06 ct. brown
February 27 – Kenny and Melissa Oliver, Rosston, AR, 3 pt. white
February 28 – Butch Hightower, Hot Springs, AR, 7 pt. white; Alberta Fling, Murfreesboro, AR, 5 pt. white; Daniel J. Kinney III, Sault Ste. Marie, MI, 2 pt. white
March 1 – No diamonds registered
March 2 – Richard Trent, Russ, TX, 20 pt. white
March 3 – No diamonds registered
March 4 – Luther Hart, Cotton Valley, LA, 1 pt. white
March 5 – No diamonds registered