Mimetite: Poisonous Contents

I had known about mimetite for quite some time before I came to own a piece of it and even after I acquired one it was a while before I learned much about it. I hope you will enjoy today’s post, which shares what I have learned about the mineral mimetite.
I have discovered that mimetite gets its name from the Greek word for ‘imitator’ because it resembles another mineral called pyromorphite. It is formed when galena and other lead-bearing minerals are exposed to the air and alter over time, so it is not surprising that it often occurs with galena and anglesite.
My mimetite specimen is yellow, but I’ve learned that the mineral can also be brown or green in color. Perfect mimetite crystals are slender hexagonal prisms, but they are very rare. Mimetite is usually found as cauliflower-shaped crusts or growing in a botryoidal habit (masses shaped like bunches of grapes) Mimetite crystals can also be barrel-shaped in which case they are called ‘campylite’.
I have not read anything that would suggest mimetite is especially hazardous, but I would advise the collector to use caution when handling the mineral as it contains lead and arsenic in its chemical makeup.
Mimetite is found in such places as: the Czech Republic, Germany, as well as in the Mexican states of Durango, Sonora and Chihuahua. It is also found in Arizona.
I had a lot of fun learning about mimetite and I hope that you have, too!

Obsidain: GlassFrom the Volcano, Part Four: Is It a Rock or a Mineral?

For the time being I am finished talking about obsidian. For my final obsidian post I would like to answer a question that some may be wondering: is obsidian a rock or a mineral?
To be honest I’m not exactly sure. To be classified as a mineral a substance must be an in-organic, naturally occurring, homogenous solid that has a definite chemical composition and a crystal structure. A rock is a natural aggregation (mixture) of minerals. Generally a rock is a mixture of more than one mineral, but sometimes it is composed of only one such as marble, which is made entirely of calcite. Obsidian is an inorganic homogenous solid, but it has no crystal structure and an indefinite chemical formula. One piece that I read described obsidian as a mineraloid, which is a mineral-like substance that does not have a crystal structure, and is of an indefinite chemical composition. This very same piece, however, also described obsidian as an igneous rock, a label that obsidian is also able to wear as it is a mixture of minerals. Most other books that I’ve read seem to call obsidian a rock, but it is still a difficult call to make.

Obsidain--Glass From the Volcano: Part 3, Location! Location! Location!

Since obsidian is of volcanic origin it could be found wherever there is or has been volcanic activity. Some important sources are: Arizona, Utah, New Mexico, Hawaii, Oregon, Japan, Mexico, the Indonesian island of Java, Guatemala, Iceland, Ecuador, and Italy’s Lipari Islands.
Another famous source of obsidian is Yellowstone National Park in the state of Wyoming. Many scientists assume that there was a volcanic eruption there many years ago, so it makes sense that one can find obsidian there. (There is actually a large outcrop of the stone in the park called “Obsidian Cliff.”) I myself found two nice pieces of obsidian in Yellowstone when my family and I went there last year. One was a nice glassy, black, translucent chip about the size of a quarter and the other was a black, nearly opaque, broken lump with beautiful spheres of white minerals in it, one of which was exposed by a break. Unfortunately, I couldn’t add these to my collection because it is illegal to remove minerals from a national park! I was, however, able to photograph them and I’ve used the photo of the little chip as this post’s picture.
Next week I will make my final obsidian post (for now, anyway) which explores obsidian’s curious properties.

Obsidian: Glass From the Volcano--Part 2

Well, I’ve kept all of you waiting long enough to read about obsidian’s uses. Here is the long-awaited post which describes how this odd volcanic glass was used in the past and how it is used today.
Obsidian is arguably one of the most useful stones in all of Creation. Like quartz and flint, obsidian breaks with a conchoidal fracture (which means that its chips look like conch shells) Anything that breaks with a conchoidal fracture can be flaked into very sharp blades (this is called 'knapping') Obsidian is no exception. In fact, obsidian has the sharpest cutting edge of any natural material! In the past people have used obsidian to make such bladed tools as arrowheads, knife blades, spear heads, saws, and axe heads. Obsidian is actually still used to make these implements by hobbyists (my self included) and for use in ocular and neurosurgeries. The reason that obsidian is used in surgery is because of the fact that it can be given a finer edge than stainless steel and therefore it leaves finer cuts that heal faster and leave less scar tissue behind.
Obsidian has been used to make jewelry for thousands of years and is still polished and cut for this purpose today. Another use for obsidian that is no longer around today, but nevertheless still fascinating is as a material for making mirrors. This was done by the Aztecs and the people of Ancient Greece. I’m not exactly sure how they made mirrors out of obsidian, but I do find the idea an intriguing one!
I hope you enjoyed today’s belated post. The next will discuss the locations in which obsidian is found.

I'm Back

Hello everyone. It's been more than a year since my last post and for that I appologize. A lot of other things have come up and I let this slide onto the backburner. I will be adding more interesting things in the near future!