At the ISG we study by specimen rather than by textbook. This allows us to learn more about all of the variables that gemstone properties can offer, rather than teaching a simple listing in a textbook.  To do this we collect as many gem and mineral specimens as we can find, buy, beg, borrow and get donated.

 

Occasionally we find things that are just so unique that they sort of defy explanation. And with so many friends in so many places world wide, the ISG has assembled one of the most unique collections of weird and unusual gems and minerals that you will find anywhere. So we thought we would  share three of these with you this week. The first was donated to us by Trent at BKK Gemstones of Bangkok, Thailand.

 

At right you see a fairly large pocket of petroleum inside this quartz crystal. This occurred due to the petroleum existing in the hydrothermal intrusion where the quartz crystal formed. As the hot water environment started to cool and the quartz crystal began to grow, the petroleum that was in the hot water was simply engulfed inside the crystal as it grew, leaving pockets of petroleum with gas bubbles inside the cavities of the quartz crystal. But here is where it starts getting weird.

 

Below you see a formation that has a lot going on with it. Not only do you have a spike looking formation of light and dark petroleum, you also have a lot of twinned crystals.

 

Twinning is when two or more crystals grow in the same dimensional space. In other words, the molecules of the quartz are so tiny and far apart that you can actually have two or more quartz crystals growing within the same place, inside each other. This is what you see below with the many points sticking up to the left of the oil spike. These are simply a whole row of tiny petroleum filled quartz crystals that have all grown inside the larger host crystal. It is actually possible to have scores of crystals growing inside each other due to twinning.

 

 

Sometimes these twinned crystals are not full formations, but are sort of ghosts of crystals. What we appropriately call phantoms. A phantom crystal is one that is actually present, but you don’t really see the complete formation because it’s sort of a….well, a phantom. At left you see a phantom crystal that is partially visible due to a cavity that contains water. This water is millions of years old and was inside this phantom crystal when the larger host crystal simply engulfed it during formation. Sort of a "now you see me, now you don’t," looking formation.

 

But here is where it really gets fun!

 

Below you see a 10x image of this crystal photographed from one very special direction. You can see the blue and yellow colors of the petroleum filled cavities inside the crystal. But WAIT! What is that? Is that a FROG? An OILY FROG?  Sure looks like it to me!

 

One of the most fun aspects of crystal study is just how weird some of the inclusions can be. And just how many people can see images in the inclusions….sort of like seeing shapes in the clouds in the sky. When I was imaging this crystal this frog jumped out like a……well, a frog. Of course the most fun I have had with it was someone over at another forums board who saw it and wondered how a frog could have been caught inside this crystal. No, no, no. It’s not a real frog. Just a really frog looking petroleum filled cavity. Thank you Trent and all of the folks at BKK in Thailand . This was just a great addition to our study collection.

Transparent turquoise crystals are extremely rare, and small. In fact, I have a lot of people question the existence of transparent turquoise crystals. But there are indeed formations of transparent turquoise crystals found in several locations around the world. The first was in the US state of Virginia in 1912, the location from which our specimen came from. For many years this was the only known location where transparent turquoise had been found. But today there are several locations around the world where this rare mineral specimen has been located.

 

As you can see above, the crystals are very, very small, averaging around 1 mm in size. And since they are on the side of the host rock formation, it is extremely difficult to get them under a microscope for imaging. But we were able to get some images of this specimen that I thought we would share today. 

Bismuth (sometimes spelled bizmuth) is a metal that does not occur naturally in crystal formation, but has a very unusual shape when artificially induced to crystallize. It is sometimes used as a substitute for lead in various medical and industrial uses since its properties are very close to lead without the problem of toxicity.

 

 

Most important to gemology and the jewelry industry is the wonderful array of colors that the bismuth crystal offers as you can see above left and in the banner of this week's newsletter. I have a lot of people look at this bismuth crystal and ask if it’s plastic or some sort of costume jewelry item. In truth, the shape of the bismuth crystal you see above left and below is due to the formation of the atoms just as with any other crystal. The shape you see is the shape that the atoms take when lining up to crystallize. The rainbow colors are due to oxidation of the surface of the crystal, with the geodesic formations offering variable colors and shapes, and can make beautiful wire wrap jewelry items, as well as other ornamental jewelry. But this is a real crystal of a naturally occuring metal. Bismuth!

 

I hope you enjoyed a little tour of some of the more unusual specimens in the ISG Student Reference Collection. The world of gems and minerals is without a doubt the most fun and entertaining study of all. Every specimen is different and you never know what you will find inside . So be sure and take some time and spend a few minutes looking closely the next time you pick up a crystal. Today a frog, maybe tomorrow a lion, or tiger, or bear....OH MY!

 

Robert James FGA, GG
President, International School of Gemology