Chapter 4, page 4
More Q & A about Quartz crystals
Q. How can I tell a crystal ball is real or fake .What kind of test can I perform before I buy the crystal ball? Thank you.
A. There are 3 non-destructive tests I know of, but two require some special equipment.
1) Specific gravity: the specific gravity of quartz (rock crystal) is 2.65. This is a measurement of the density of the mineral in relation to the density of the same volume of water. You can easily weight the sphere dry, but you need a special type of scale to get its wet weight. You must suspend the sphere by a fine thread in a container of water and weigh the sphere. Once you have the dry and submerged weight, then you put the values into the following formula:
Specific gravity = weight in air / (weight in air minus weight in water)
Quartz is 2.65 times denser than an equal volume of water. Plastic is less. So are most glasses, except for lead crystal which may be greater.
2) Quartz is optically uniaxial, so if you place the sphere between two crossed polarizer plates and rotate the sphere you may be able to find a uniaxial optic axis figure. It looks like a large fuzzy cross and due to the thickness of the sphere would have multiple color bands coming out from the cross' center. Two lenses from an old pair of polarized sunglasses can be used to check this property. Be certain you rotate one of the two lenses until the field goes black or dark when you look through both before inserting the sphere between them.
3) Spend some time looking into the sphere with both the naked eye and a good hand magnifier (10X preferably). If with the naked eye you see fluid swirl marks, the sphere is glass or plastic. Quartz has not formed from a melt so it would never show swirl marks. Under magnification, look for small spherical bubbles. If present, the sphere is not a natural material. Except for lava flows, nature almost never produces perfect spherical holes, especially not in rock crystal. I have seen these bubbles in both glass and plastic spheres.
4) Look at the internal flaws. Are milky zones or cloudy patches present? If so, it could be quartz. Check these with the hand lens (above) to make certain these zones do not contain small round bubbles. Glass, plastic, and quartz all fracture with a conchoidal or shell-like break. I do not recall fracturing being very common in plastic or glass spheres, but it is a relatively common flaw in quartz spheres. Often you may get a rainbow light reflection off quartz fractures, but if present in glass or plastic, I would expect the same effect.
These are the principal non-destructive tests I know of.
You could always check the sphere's hardness with the sharp point of another quartz crystal, but the seller might get upset if you scratched his/her glass or plastic sphere. Quartz will only scratch quartz with considerable difficulty since they are the same hardness. Be certain to check with the owner before attempting this!
Q. On a recent trip to Arkansas, I stopped at Miller Mt. to collect for a few days, Upon returning home and cleaning them up, I found several gwindeles ranging from 1 1/2" to 6" long and the size of my hand. My question is " Is this crystal formation common in Arkansas? I had thought they were more Alpine in origin. Thanks John HuckA. I would be very surprised if you truly have gwindels from any site in Arkansas. You are correct about this form being more typically from Alpine-type veins. I have been collecting Arkansas quartz for 35 years and have many specimens from Miller Mountain in my collection. However I have never seen a gwindel from Arkansas. Perhaps you have found some fractured and rehealed crystals which generally may exhibit a twisted habit. If the crystals have a cloudy zone internally and are twisted or bent, then they are not gwindels, but instead are due to repeated fracturing and rehealing of those fractures.
I would certainly like to examine a few of your specimens to see what you are talking about. Perhaps you could mail me a couple to look at and then I could send them back to you. Email me and I'll send you my snail mail address.
Q. I've collected quartz crystals from the Mt. Ida area for many years....I'm curious to know more about the triangle formations on some faces of a very few crystals...my brother who has collected in this same place for many years also says they are called "communicators"......what can you tell me about these triangles ?
A. Dan, the triangular faces which you describe are on the termination faces (those that make the point or terminal end) of the quartz crystals. Quartz crystals typically grow by adding layers of silica onto the terminations. Raised triangular shapes reflect the general shape of the individual face and represent where the last crystal was added. Not enough silica was present to fill the face completely out to make a new flat surface. Triangular pits often represent solution features where silica for some reason was being dissolved from the terminal face. Rarely, triangular pits may represent holes left by very rapid face growth. In this instance, a tiny "stringer" or needle like hole may extend down from the face into the clear crystal underneath. Mystic folks like to call crystals with these features "recorders" and they are (in a scientific sense) in that they record the chemical history of the solutions that were in the pocket as the crystal was growing or dissolving.
also....I have many blue phantoms and I know the color is caused by another mineral in there
Essentially all the specimens with black and "blue" (really gray) inclusions that I have had examined chemically turn out to contain shale, a rock rich in aluminum. Shale is not uncommon as a host rock and with all the movement that took place (geologist's call this movement structural readjustment) while the veins were forming, it is reasonable to assume that at times particles of shale were being washed through the veins by fluid movement. Anything that could wash into the veins during crystal growth could and often was captured in crystals.
...what mineral can cause an inclusion to be blood red in a quartz crystal?
Very few minerals could give a blood red color to an inclusion. Either iron oxide, which is rather scarce, or cinnabar (mercury sulfide) come to mind. In the mercury district in Pike County, during mining some small double terminated crystals that looked like Herkimer diamonds were recovered that contained tiny spots of cinnabar and wires of stibnite or jamesonite. None of these have been reported from the major crystal deposits of the Ouachita Mountains, however. I think I would really need to see a couple of these crystals with the red inclusions to know for certain.
Q. Can you tell me if Arkansas produces Dauphiné and/or Brazil twins?
A. Morphologically speaking, both brazil twins and dauphine twins from Arkansas as recognizable twins appear to be extremely rare. However, etchings of crystals from Arkansas indicates that they are very common. During World War II, most of the eye-clear quartz that was submitted for optical and electrical testing was twinned and failed to be usable. I think only about 2 % was untwinned. The problem is that although it might look like a single untwinned crystal, it usually is not! Some specimens show a feature on the prism faces that look like zones or patches of slightly different reflection or luster. These patches are bounded by curved to zigzaggy lines. This is an indication that the "crystal" is twinned.
Q. How do I find out about staking a claim for my own crystal mine? I'm wondering how much it costs, the terms of a claim and who to contact to arrange such a thing. Lisa
A. Dear Lisa, The days of "staking a claim" for quartz are gone. The procedure is now by the practice of contract, just like for the commodities of sand and gravel, field stone, or crushed stone. This entire procedure changed about 10 years ago. Nowadays, if you locate a potentially minable deposit of quartz crystal on National Forest land, you must put the property up for sealed bid to the District Forest Ranger. The Ranger will visit the site and evaluate it for a number of factors, including actual size, potential environmental impact, potential visible impact, and so forth. The Ranger determines the actual area to be bid on, along with any restrictions that may be attached to the contract. Then, the property is listed on a sealed bid form and mailed out to several hundred people, who have requested that their name be kept on the mailout list. Any or all of these people have the right to visit the property and bid on it. To win the contract, you must be the highest bidder, not just the locator. This new system has taken all the incentive out of it for individuals to search for new deposits, since just anyone on the list may have a chance to bid.
If you wish to know more about these procedures and how to get on the list, I suggest contacting John Nichols, Forest Geologist, Ouachita National Forest, P. O. Box 1270, Hot Springs, AR 71902.
As far as quartz deposits on other than National Forest lands: some deposits may be located on BLM or Corps of Engineers governed lands, both of which are under their own sets of rules and regulations. Also, with privately owned lands, it's between you and the land owner as to what you work out financially. The government is not involved.
As you probably have realized by now, the most important thing in the entire process is to know who or what government agency controls the land you find the quartz on because that will determine what procedures you must go through to obtain the rights to dig quartz commercially.
Mikey
Ch 4, page 4
AskMikey@RockhoundingAR.com revised July 1999
© Rockhounding Arkansas 1998 http://rockhoundingAR.com