Corundum Fail

I initiated spring break with three of my best friends by traveling about an hour away to go try to find some rubies and sapphires. The corundum in the particular area we visited is mostly of a pink color, thereby qualifying it as pink sapphire rather than red ruby. The red rubies were our main target for today’s trip, however. Another friend had success at this location earlier in January and told me about the spot, thereby sparking my interest in visiting this area to try to find my own corundum. My friends have never been out to find their own gemstones, so I was really hoping that we would find some so they would have a good time.

The corundum crystals in this area are found in weathered remnants of pegmatite. Think of a pegmatite as granite with much larger crystals making up its composition. Pegmatites are very similar to granites with respect to how their compositions are often quite varied. A pegmatite predominantly consists of feldspar, mica, and quartz. Therefore, it makes sense for the corundum crystals in this area to be found near veins of quartz. Additionally, Jenna and Marissa noted how beautiful the shiny flakes in the soil we dug up were today. I would guess that these flakes were of mica even if I had not known about the corundum crystals being found in a pegmatite just from their consistency in the soil.

I would post the name of the area we went to if it seemed worth it to ever go back there to search more…but it was absolutely not worth it. To put it simply, it was just a wreck. It was nothing like I expected it to be. The area we were digging in was typical North Carolina red clay. I expected that. The rains from earlier this week made the soil pretty manageable. I expected that. What I did not expect was having a twelve foot deep pit in the ground dug (backbreaking work) without coming across a single rock. We did not even find a single piece of quartz here either. My friend who found a sapphire in this area in January found a lot of quartz which served as an indicator of becoming close to the corundum vein. I could go dig through the red clay in my backyard and find quartz. Quartz is very common in the soils of the Piedmont.

So much of what I read online about this spot emphasized that there would be a rock layer about nine or ten feet deep which held the corundum we hoped to find. There is a small stream which flows along this property, so I hoped that rock layer would be at a depth of about nine feet as the online resources emphasized. Well, we did not find it. Jenna commented that she liked how the soil layers changed color because we were not finding anything else in our pit. Once we got about nine feet deep in our pit we were becoming very discouraged. We did our homework before setting out to start searching for corundum crystals today. What baffles me is that the soil in this particular area did not have even a single piece of weathered rock in it. This was such a bummer.

The look on my roommate Jenna’s face when I pulled out our gear was pretty priceless. Here she is hard at work!

So many gems, so little time

My spring break is coming up soon! I plan on spending at least a few days out getting some new minerals. You could have probably guessed that would be my plan. My friends and family know how excited I am about these trips and have asked me to give them smaller, less awesome versions of the minerals I find. Please check back during the first full week of March because I will have several posts about where I go, what I find, overall impressions, and helpful directions. Seriously, one of the hardest aspects of planning these mineral-hunting trips is finding out a proper address or at least a good parking location. My plans are to travel in the mountains with maybe one stop in the foothills or piedmont.

Garnets (A²⁺₃B³⁺₂Si₃O₁₂)
*A represents Ca, Fe²⁺, Mn, or Mg
*B represents Al, Cr, or Fe³⁺
I got a handful of nice garnets last year with my cousin Connor. I have a greater appreciation for garnets ever since I did some more research on a whim a month or two ago on my own time. I did not have an assignment to learn more about geology and mineralogy–I just wanted to learn more. Garnets come in almost any color. I knew about some of the green garnets such as demantoid garnet and became fascinated by them. Grossular, tsavorite, pyrope, almandine, and spessartine are several other types of garnet which are also common. Garnets are colored by calcium, iron, and manganese. Garnets have a hardness of 6.5-7.5, so they are very desirable for jewelry or as an abrasive in powdered form. Almandine garnets are very common in North Carolina’s garnet-mica schists. A schist is a metamorphic rock which can have many different types of minerals within it. The rock which undergoes metamorphism in order to produce a schist is normally a felsic igneous rock or shale. Felsic igneous rocks contain more than 75% of a felsic mineral such as plagioclase, orthoclase, or quartz. These felsic rocks are characterized by being abundant in silica.

Kyanite (Al₂SiO₅)
I became fascinated by kyanite when I went on a hike with one of my professors to Crowders Mountain in Gaston County, North Carolina. This mountain is a monadnock which remains today because the surrounding landscape eroded away from it. It is a beautiful area which I have visited in every season. Crowders Mountain exists in Crowders Mountain State Park which will protect it in the future. Originally, people wanted to mine the kyanite which Crowders Mountain is full of before it became protected. Kyanite is a blue-grey mineral which has a hardness of 5 or 7 depending on the way it is cut. It is recognizable because of its color as well as because of its elongated crystals which look similar to columns. It occurs in the metamorphic rocks schist and gneiss as well as in igneous pegmatites. I think it is interesting that kyanite is used very frequently in spark plugs. It seems like a waste of a very beautiful mineral. I would LOVE to find some new kyanite. I definitely will not be trying to get any of the kyanite from Crowders Mountain. My sights are set on somewhere much more remote near the border of Tennessee.

Corundum (Al₂O₃)
North Carolina’s rubies and sapphires are very famous. That is a good enough reason for me to want to get some. Corundum includes the aluminum oxides called sapphires and rubies. Sapphires are colored based on the trace amounts of elements which are in them including iron, copper, and magnesium. Chromium is the element which makes a ruby red. So, a ruby and sapphire are the basically same thing. Both make excellent gemstones for jewelry because they are very hard (basically only diamond and “fake-diamond” moissanite are harder). You may have seen clear corundum (lab created, of course) used for a watch face so that it would not get scratched. Corundum crystals are easy to spot because of their hexagonal structures.

Wish me luck! I am very excited to find some beautiful specimens. Maybe I will even find something I can have cut!