Iron Pyrite -- "Fool's Gold"

Pyrite is an iron sulfide generated by sulphur reacting with iron present in sedimentary rock (limestone & sandstone) in a reducing environment. It comes in an astonishing array of forms -- from discoids (also known as sunflowers), to suns, to perfect cubes -- all in the same glittering, glassy, golden shade. When found with quartz crystals (as it often is), the encrustation of pyrite causes the quartz to form delicate, needle-like points unlike any you've seen before! Pyrite is also part of what makes Lapis Lazuli (a vivid blue rock with pyrite veins) such a popular stone for tumbling, beads, and carving.

Iron Pyrite has been so often been mistaken for gold that its better-known name is "fool's gold." It has a warm yellow color, it's metallic, and it glitters and sparkles just like the real thing. So how can you tell if you've found gold or simply fool's gold?

1. Try using a straight pin to stab the specimen. Gold is a very soft metal and will bend or break when you do this; iron pyrite is much harder and won't budge.
2. If you have a 10x magnifier (or loupe), examine your find closely. Pyrite has a cubic structure; gold does not.
3. Take a magnet with you. Iron pyrite will stick to the magnet because of its high iron content; gold will not.
4. You can also use a drop of nitric acid to test your specimen (caution is advised). Nitric acid will turn iron pyrite black, but gold will remain the same color.

To complicate things even further, pyrite and gold are often found in the same locations. If you're out gold-panning and think you've found gold, look closely. If it's floating all over the pan, it's just pyrite. But if it settles to the bottom, you've gotten lucky!

Find out more about prospecting for gold at Gold Prospectors Association of America.

Gold-panning is a fun and inexpensive hobby. Find what you need: Gold-Panning Equipment.

You can also find gold (along with old coins, jewelry, and even meteorites) with a metal detector!

Stony Meteorites

Stony meteorites, or "stones," are by far the most common among all observed falls, but once on Earth they keep a low profile. As most of them are the remains of the crust and mantle of asteroids, they greatly resemble ordinary terrestrial rocks. Stony meteorites contain too little of the nickel-iron alloy that characterizes iron meteorites to register with a metal detector, a favorite tool of meteorite hunters. However, most will cause a magnet hung from a string to swing toward them, and this is one of the first tests a meteorite hunter will employ once they've found a likely specimen.

A few stony meteorites are thought to have originated on larger celestial bodies, such as the Moon and Mars. One specimen in particular, found in Antarctica in 1987, is believed by some scientists to show traces of ancient life on Mars! You can find more information on this controversy, as well as many other interesting facts about meteorites, in O. Richard Norton's book, Rocks from Space.

Because of the difficulty of finding them, stony meteorites are less available on the market than are the irons. We are very pleased to be able to add stony meteorites to our product offerings, in a wide range of sizes and prices.

Read lots more about stony meteorites in our LEARN MORE section.

Making Beach Glass With Your Tumbler

One of the most common requests we get via email is for directions for tumbling glass to recreate the frosted matte finish found in glass washed up on the beach. A rotary tumbler is recommended, as a vibratory machine won't give you the soft curves that are part of the seaglass look.

A few things to keep in mind about tumbling glass, in general:

*Safety: Handle broken glass with care! If you decide to break the glass yourself, put the glass objects in a heavy fabric bag before wielding your hammer, and wear both safety goggles and gloves. You can either choose to work with broken pieces of everyday glass (like bottles and jars), or for more variety in color and size/shape, try our slag glass.

*Out-gassing: Glass -- whether manmade or natural (obsidian) -- produces gas during the process. Check your barrel at least daily, and "burp" it if it shows any sign of swelling. You may also try adding a small amount of baking soda to your mix to minimize the gas production, though not during any final polishing step.

*Cushioning your glass: Glass chips easily, so you should add something to your load to slow the process down. You can use plastic pellets or a variety of other materials to do this, such as: corn syrup, cornstarch, sugar, molasses, rice hulls, gelatin, sawdust. You will need to experiment to find the right level, as too much thickener will make each step take longer than necessary.

*Rock hardness: Don't mix the glass (which is about Mohs 5) with any harder material.

Follow the regular directions for tumbling that came with your tumbler (or you can find them in our LEARN MORE section), with these changes:

*Step One: Process using 120-180 grit silicon carbide if you need to remove a lot of material. Otherwise skip this step. Cushion your load. Check the progress every day, which incidentally will relieve any gas build-up in your barrel. You may not want to do this step for more than two or three days. Experimenting is the heart of creating seaglass!

*Step Two: Use 320 grit silicon carbide and a cushioning agent. Check your progress daily, and stop when you've gotten the effect you want.

Instead of commercial grit some people just use ordinary beach sand -- if you want a lot of variation in your finished product, this might be for you.

For directions on how to give your glass a high polish, or just to browse our new online resource, visit our LEARN MORE section.

Geology Word Puzzler

What's the proper name for the cat's eye effect found in tigereye, cat's eye chrysoberyl, fiber optic glass, and other rocks and minerals?

Chatoyant: (shuh-TOY-ent) having a changeable luster or color with an undulating narrow band of white light. From the French, chatoyer: to shine like a cat's eyes.¹

Alternately, gemstones that show a star pattern of light (like star sapphire or star diopside, a.k.a. "Star of India") are called asteriated, from the Greek for "starry."

¹From Merriam-Webster Dictionary online.

We'd love to hear from you! Have questions or comments about the new site, or just want to tell us about your latest rockhounding adventure? Email us at we_rock@mamasminerals.com!

Read about rose quartz, geodes, and identification of rocks and minerals in the Fall 2006 issue of RockZ NewZ

Read about rose quartz, geodes, and identification of rocks and minerals in the Summer 2006 issue of RockZ NewZ

Read about fluorite, fluorescent minerals, and cleaning quartz in the Summer 2005 issue of RockZ NewZ.

Read about vanadinite, building fountains, and identifying meteorites in the Winter 2004 issue of RockZ NewZ.

Read about celestite, pearls, and how to choose the right tumbler in the Fall 2004 issue of RockZ NewZ.

Read about malachite, tumbling grits, and how to pan for gold in the Summer 2004 issue of RockZ NewZ.

Read about amethyst, fossil preparation, and field tools for the rockhound in the Spring 2004 issue of RockZ NewZ.

Read about galena, petrified wood, and collecting micrometeorites in the Winter 2003 issue of RockZ NewZ.

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