Mineral Crystals - Including How to Test for Gold versus Pyrite aka Fool's Gold
A quick note. When you are done here, there is the minerals.usgs.gov table-of-contents page for crystals; hover over each of the pics there to see the destination URL at the bottom of the page. And there is the USGS search query results for gold page; interesting stuff there as well.
Crystals and Rock Hounding Are Fun!
And it can provide hours of enjoyment. It is a nice feeling to discover a thing of beauty in a sea of red herrings.
Your basic tools for your crystal search adventures are a small rock hammer (pointy on one side, flat on the other), gloves, wrapping paper for your newfound gems, and safety glasses (even if you already wear glasses). The proverbial canteen or bottle of water and a first aid kit aren’t a bad idea either; not to mention a GPS cell phone; and of course, a backpack or equivalent to carry everything.
Rock hounding on Federal and State lands is usually not a problem; in fact, they are generally downright benign about it. Usually, a backpack-full is no problem. Many times, even a car trunk-full is no problem. If, however, you show up with an empty dump truck; then it’s a problem.
It is always best to contact the local rock hound group to find out what the rules are. Besides, since when is networking not a good idea? At least find their website to see what they have to say.
As an example, suppose the area you want to peruse happens to be managed by the U.S. Forest Service. It turns out they apparently are not the same happy campers as the other agencies. Anything over 2-3 crystals or other pieces and the words “permit” and “required” suddenly enters their vocabulary.
Your local rock hound group always knows who manages the land and what the rules are. Plus, they'll have all sorts of other useful information.
The chemical name for benitoite is barium titanium silicate in crystal form. Benitoite seems to only be found where the minerals serpentine and/or natrolite happen to be, and then only rarely. Light-blue in color. Gemstone quality is extremely rare. Crystals cost a lot less, but the price can still get up there. Interestingly, it is California's official state gem.
Tourmaline is probably the favorite crystal for both mineral and gemstone collectors. This has to do with:
A. Tourmaline crystals are bright and beautiful.
B. Tourmaline crystals come in just about every color there is.
C. Tourmaline crystals don’t cost a fortune.
Amethyst is a light or dark purple variety of the mineral quartz. As with most quartz crystals it is usually translucent. The chemical formula is SiO2. The purple color comes from the presence of manganese. However, it has been claimed ferric thiocyanate and sulfur have also been detected in the mineral. Amethyst crystal will eventually lose its color over time when exposed to sunlight. Amethyst crystal exposed to heat will turn yellow.
Calcite crystals are apparently the crystal nobody loves. Calcite is the mineral form of calcium carbonate. This mineral is the bane of water treatment plants. Where there is water, calcite crystals are soon to follow. These crystals and other forms of calcium carbonate accumulate and clog up everything in sight. It is an going project by industry and government to find something which will dissolve the calcium carbonate without the collateral damage of poisoning the water.
Carbon Crystal ( Diamond )
Crystal Carbon - Diamond
Diamonds are diamonds. What more can be said?
Actually, a lot can be said. Diamonds come in many colors and tints; not all of them good. Even more important, there are many grades of quality. It is interesting how the grade changes, depending on whether you are the buyer or the seller. If you intend to buy or sell a diamond, it would behoove you to extensively research the subject first.
Gold and Pyrite / Fool's Gold
Pyrite Crystals - Fool's Gold
Crystal Iron Pyrite
Iron Pyrite has the chemical composition of FeS2.
Here is how to tell the difference between gold and pyrite, aka fool’s gold:
Both are yellow, but of different tones. Gold is golden to silvery yellow. Pyrite is pale to medium brassy yellow.
Gold shaped as crystals are rare. Pyrite shaped as crystals are common.
Physical tests are usually what decides the day.
Gold is soft; pyrite is not. Scratch the mineral with a knife blade. Gold is softer than pyrite and will be scratched or cut. Pyrite cannot be scratched. Beware, a mineral called chalcopyrite which looks like pyrite and can be scratched. However, its brassy, yellowish color will give it away.
Gold does not smell; pyrite does. Forcefully rub the specimen with a hard object. Gold has no odor. Pyrite smells like sulfur or rotten eggs.
Gold is malleable; pyrite is not. Strike the specimen with a steel hammer. Gold will flatten or change shape and is not known to break. Pyrite will give off sparks and generally act like any other hard rock hit with a hammer.
Barite on Fluorite
Crystals Barite and Fluorite
The chemical name for barite is barium sulfate.
The chemical name for fluorite is calcium fluoride.
Both are high-demand industrial minerals.
The mineral quartz is composed of oxygen and silica. Quartz crystals can form when water percolates through fragmented rock. Pure quartz is a high-demand mineral for multiple industries.
Crystal Carbon ~ Yellow Diamond
12.76 Carat Pink Diamond
Orbicular Lapidary Rock Art
Bonus Section - Another Aspect of Rock Hounding. Orbicular Lapidary Rock Art, e.g., jasper, llanite, bauxite, obsidian, marble, petrified wood, and more. And info and pictures. Maybe will be of interest; maybe not.
Orbicular Rain Forest Jasper
Introduction to the Hobby of Lapidary Orbicular Rock Art
One definition of lapidary art is the orbicular transformation of mundane, and not so mundane, rocks into beautiful spheres. The conversion from one to the other is a long and complicated process. It is both a science and an art.
First one has to determine which nondescript rocks are capable of being transformed into beautiful spheres. Training and experience are required to learn this skill. It is also an art.
Once you have selected your specimen, out come the tools. Starting with a rock-saw, and then using other tools; you trim your specimen to as round a shape as is practical.
Next, you toss/heave (gently place) the thing into a sphere-making-machine aka tumbler aka polishing machine. You may or may not throw in a bunch of grit along with it; it all depends.
Eventually, given several factors, a beautiful (and sometimes valuable) sphere of beauty may be the result.
Lapidary orbicular art is a hobby enjoyed by many. It’s even been known to turn into an obsession; working with things of beauty can do that to you…
Jasper is a product of previous volcanic eruptions. Formations occur when silica rich rhyolitic ash flow is subjected to rapid cooling. Quartz and feldspar crystallize in spherulites or needle like crystals.
Llanite is a brown granite containing crystals of blue quartz, feldspar, biotite, apatite, and zircon.
Obsidian is another by-product of volcanic eruptions. There are many different varieties.
Orbicular Bauxite / Boksit
Bauxite / Boksit
Bauxite (boksit) is as mundane as mundane gets. It is a common mineral mined to produce aluminum.
Orbicular Petrified Wood
Petrified wood are fossils. When a fallen tree is buried in moist earth, a mineral transfer can sometimes occur. Given sufficient rain, the earth’s minerals can dissolve into the tree. If in time the minerals dry out and the original tree material disappears, the tree literally becomes a rock. If the mineral saturation is extensive, the rock looks like the original tree and is then called petrified wood.
Marble is a type of metamorphic rock. Metamorphic rocks are rocks changed from their original igneous, sedimentary, or earlier metamorphic form. Metamorphic marble (so to speak) is Metamorphic rock consisting of coarse/fine grained re-crystallized calcite (aka limestone) or dolomite. Marble comes in a variety of colors; including white, gray, red, pink, and black.
"Septaria" is a broad term describing the mineral formation wherein one mineral fills and embeds the pores of another mineral.