What's in a name? That which we call a rose By any other name would smell as sweet.
-- Romeo and Juliet, Shakespeare
Stand on a rock (or a car if you live in a big city) and cast your eyes on any non-living objects around you. Nearly all will be mostly silica.
Cars and other metal objects are a special case. Mankind has gone to a lot of effort to find metals in their hiding places, refine them, and bring them to our nests in the city, so there's an unnatural lot of it there. Paper, wood, cardboard and so forth was once living, so they don't count either. In the countryside, where what you might see is dirt and rocks, this is literally true.
Silica is the more common name for silicon dioxide - Si02. One molecule of Silicon for two molecules of Oxygen. That's "Silicon", not "Silicone" (the Hollywood starlet's best friend). Silicone is completely different stuff. Silicon is element 14 in the periodic table. Silicone is a complicated goo made of a lot of elements.
Here’s a related question. What is the second most common element in the Earth’s crust? The first is oxygen. Water, which could be called “hydrogen dioxide”, helps make oxygen the most common element. The fact that oxygen is also two thirds of silica helps too. The second most common element is silicon. So, you might think of silica - silicon dioxide - as being like water because it's everywhere.
Most rocks you pick up anywhere in the world are mostly silica. Quartz is. Sandstone is. Chert, flint, and even schisty old mica are mostly silica. And so are chalcedony, agate, and jasper. The difference is what is mixed in with it; how big the microcrystalline bits are; and how these bits are lined up in the rock. Since they’re all mostly the same down at the most basic level, there’s a lot of confusion about it at the rockhound level.
Geologists don’t have this problem. They assign a highly specific name to every sub-variety of every rock. You can get an advanced degree at just about any egghead factory by discovering a new rock that is ever so slightly different from every other rock. There are global committees with international meetings in comfortable vacation spots (Nice work if you can get it!) just to make sure that everybody toes the line about using only the oh-so-correct names. But what’s a rock jock to do? Most of us have to make a living and can’t take the time to learn the difference between jade that is “jadeite” and jade that is “nephrite”. The difference was only discovered fairly recently -- in geologist years.
After getting red in the face arguing about it a few times with other rockhounds, I decided on an elegantly simple way to tell the difference.
· Jasper is opaque. You can’t see past the surface.
· Agate is translucent – slightly transparent.
· Chalcedony includes both.
To prove just how complicated this is, Geology.com suggested their own formula for deciding what the name of a rock should be. They give you five choices. Four of the five are "chalcedony". The fifth is "coarsely crystalline quartz" and two of the four are "agate-that-is-chalcedony" and "jasper-that-is-chalcedony". Real helpful!
There! Feel free to use my definition. Or not. I won’t argue with you about it.
Especially in certain rock forums, a battle rages over what name to use for certain rocks. Since I sell rocks, it’s important to me because it’s important to the people who buy my rocks. (It’s not important to me for any other reason.) I agree with Romeo. A rock by any other name would still look great.
But in certain rock forums, which shall remain nameless in this discussion, the fight goes on! The specific identification of a rock ranks in importance right up there with the war between Lilliput and Blefuscu over which end to break on your boiled eggs.* But I have to admit, it can be a critical difference, at least in terms of money.
For example, the picture shows my dad’s polished piece of “classic” Yellowcat Wood. This might be the most valuable rock found in Utah. (Excepting red Beryl – another story entirely.) There are public cases where Yellowcat Wood has fetched prices in five figures at prestigious auction sites.
Wh-a-a-a-t? (Sez I.) It’s just a rock!
I call this the “Inverted Jenny Syndrome”. People have paid almost a million bucks for just one 24 cent “Inverted Jenny” stamp. Two conclusions: (1) With the right marketing, you can make people believe that anything is valuable. (2) Some people have w-a-a-a-y too much money.
I have more of a rock that I think is is close relation to Yellowcat Wood. Because I can't think of a better name (Suggestions are welcome!) I call it Yellowcat Bark.
I may not know for certain what it is, but I know for certain that it polishes to a beautiful shine. My friend Ken sent this picture of some he polished. I posted it at my Rock Pictures page.
I have spent a lot of time trying to determine whether the rock I have decided to call, “Yellowcat Bark” is anything like “Yellowcat Wood”. I’m pretty sure that my dad found it in about the same place where they once found Yellowcat Wood. (There’s certainly none there now.) But it’s also clearly not the same as “classic” Yellowcat Wood. I don’t want to mislead anybody about what it is, but it might be as valuable as Yellowcat Wood if I could attach the right name to it.
So, the name you attach to a rock does make a difference.
-----------------------------------
* If you’re confused, this is from the most famous story in Swift’s book, Gulliver's Travels.