Meteorites: The Celestial Objects Existing on Earth

The human fascination for what lies beyond earth has always been intriguing, even in the primitive times. By the virtue of this unrelenting fascination and general curiosity, we have succeeded in traversing the space that exists further than our planet.

Our excursions to space only started during the later years of the 20th century. On the other hand, Earth has been welcoming foreign bodies from in the form of meteorites thousands of years before our missions to space in the 20th century.

Meteorites are the infinitesimal debris originating from a variety of celestial bodies within our solar system. They are mostly the fragments of comets, meteoroids, and asteroids, which withstand the atmospheric entry to our planet and fall on Earth. In this article, we will discuss some basic aspects of these minor spatial bodies that end up on our planet and deemed valuable specimens by many stone collectors, hobbyists, and professionals, such as geologists, astro scientists and natural history museums curators.

Meteor, Meteoroid or Meteorite?

There is a general confusion regarding the terms meteors, meteoroids, and meteorites. Many people wrongly interchange these terms. So, before we move to discuss meteorites in detail, it will be fitting to lay this confusion to rest once and for all.

  • Meteor: The term is actually used to describe the streak of light blazing through the atmosphere due to burning celestial debris.
  • Meteoroid: It is that interplanetary object that burns up in outer space to produce a ‘meteor’.
  • Meteorites: They are those few meteoroids and their remnants that don’t get vaporized upon entering the atmosphere of earth.

Micrometeorites

Whenever we talk or think about spatial and interplanetary things, it is usually underlined with the assumptions of colossal masses and gargantuan planetary balls. But it is interesting to note that most of the interplanetary stuff that ends up on earth is really small in size, even by the non-astronomical size and dimension standards.

For instance, most of the celestial mass that ends up on earth has a size smaller than 100 micrometers per specimen and hence called micrometeorites. All these micrometeorites don’t survive the atmospheric entry and transform into dust. But this dust from far off planets and stars collectively add somewhere between 30,000 and 40,000 tons to the mass of earth every year.

Classification of meteorites

Classification of meteorites is usually carried out on two criteria i.e. how they are found on the ground and which elements they are made of. Let’s have a look at them one by one.

Finds and Falls

Meteorites that are discovered way too long after their fall on earth are called Finds. On the other hand, meteorites falling that is witnessed by observers and later collected through planned quests by collectors are called Falls. The latter type of meteorites is more sought-after among the collectors. However, some exceptional Finds specimens also get good money to its discoverers.

Iron meteorites

These meteorites have the prefix of iron because they are primarily (90-95%) made of the metal. According to astronomical studies, iron meteorites are believed to be part of the inner mantle of planets that perished hundreds and thousands of years ago. It is also said that iron meteorites found on earth are mostly the fractions of asteroids present in the belt of interplanetary objects between Jupiter and Mars.http://streaming.yayimages.com/images/photographer/brandonhot/343eec9eb3ce52ab66bbadf4b2c2b649/iron-meteorite.jpg

Unlike normal geological stones, iron meteorites are way heavier. This exceeding weight is due to the densely packed iron molecules. If you have ever lifted a cannonball with your bare hands then you can get an idea of how heavy an iron meteorite is. Besides iron, traces of nickel and other metals are also present in this type of meteorite.

Kamacite: An Alloy Found in Iron Meteorites

Some iron meteorites also contain a naturally developed alloy of iron and nickel called Kamacite. The formation of this alloy introduces crystallization changes in the meteorite that can be seen through aesthetical patterns and color combinations when the specimens are cut, polished and treated by a mild nitric acid solution.

Stone Meteorites

These are the most abundant meteorites found on the earth surface. Stone meteorites are made of the external crust of interplanetary bodies and hence look pretty similar to any earthly rock specimen. People with no meteorite hunting expertise can’t tell them apart.

However, stone meteorites that have recently fallen on earth get a peculiar black crust because of their smoldering upon entering the earth’s orbit. Stones meteorites have lesser demand in the collector’s industry in comparison to iron meteorites. However, there are some special specimen stone meteorites that are sought-after because of their visual appeal and history.

Chondrule-laden Stone Meteorites

There are some stone meteorites that contain unusual, grainy and vibrant inclusions called ‘chondrules’. This ‘impurity’ makes meteorite specimens more attractive. Apart from that, collectors are also intrigued by these specimens because of the history of chondrules.

It is believed that chondrules were once part of the solar nebula. This means these tiny grains are the most ancient item present on the earth surface even predating the formation of our planet and the life that has ever existed here.

Miscellaneous Types of Meteorites

Besides these two mostly occurring meteorites, some other rare specimens are found.

Stone-Iron Meteorites

They make up two percent of all the meteorites found on earth surface. Because of this extraordinary arrangement of two different materials, these meteorites are popular among collectors, which also make them relatively expensive. They are often framed or showcased after receiving some treatment (polishing and acid treatment).

Lunar and Martian Meteorites

Some really rare meteorites have also been discovered that originated with the impact of other celestial bodies on the surface of the Moon and Mars. Lunar and Martian meteorites are extremely rare and therefore can be sold with a hefty price tag. They are often priced as per their weight like any precious gemstone or rare earth metal.

You can learn more about observing and finding meteorites on the Astronomical League website.

Understanding the Mohs Scale and the Durability of Gemstones

Diamond gem with reflection on blue background
Diamond gem with reflection on blue background. Photo: Big Stock

Whenever you talk about the hardness of minerals and gemstones, you might have heard people from the industry measure the hardness on the Mohs Scale. The rating on the Mohs scale is one of the most important tests for the quality of mineral specimens and this comes in handy when you are looking to purchase jewelry.

For example, if you buy a ring that contains Gypsum, you might want to rethink that since this stone has a hardness rating of 2 on the Mohs Scale, which is low and subsequently it may often get scratched due to the continuous movement and friction to other materials when working with our hands. Deciding to wear it as an earring would be more practical. We are going to take a look at exactly what is the Mohs scale and some other qualities of gemstones that allow us to properly determine their durability.  

What Is The Mohs Scale?

The Mohs Scale or the Mohs Hardness Scale was created in the early 1800s by a man called Friedrich Mohs. He was considered to be one of the most renowned mineralogists at the time. He created this measure to find out and determine the comparative resistance that a mineral has to scratch.

The Mohs Hardness scale was revolutionary for the mineral and gemstone industry because right after its creation, people were able to use this scale to classify the durability of gemstones. However, if you are looking for a truly durable gemstone that can withstand the test of time, there is more to determining just durability besides the hardness on the Mohs Scale.

This scale is essentially based on a resistance factor that a mineral has to scratch. It is considered to be the only characteristic that is used to measure and determine the rank of the gemstones on the scale.

According to the findings of Friedrich Mohs and the Mohs Scale that he created, a gemstone can only be scratched by another gemstone that ranks higher. For instance, you cannot expect Topaz to be able to scratch Quartz because Topaz has a reading of ‘8’ and Quartz has a reading of seven. That means Quartz is softer than the Topaz. Similarly, you can expect the Corundum to be able to scratch Topaz because the Corundum registers at ‘9’ on the Mohs Hardness Scale.

It’s important to keep in mind that the Mohs Scale is not necessarily a linear one. This means that even though diamonds register at a reading of 10, they are not 10 times as hard as Talc, which registers as ‘1’.

The Mohs Scale is only a measure of resistance that a stone has to surface scratching.

While the Scale is considered to be one of the most important factors in determining the durability of a gemstone, it is only a single aspect of it. The overall durability of a gemstone can be different from the surface resistance that it has since surface resistance is only one factor when testing durability. For instance, an emerald has a Mohs Scale rating of 8 but it does not wear as well as a Topaz which also rates as 8. This is because there are additional characteristics within the emerald stone that make its overall durability different.  

Other Factors that Determine Gemstone Durability

Rose Quartz Healing Gemstone
Rose Quartz Healing Gemstone

If the Mohs Scale is not enough to determine the overall durability of a gemstone, what are the characteristics of gemstones that make them durable?

The additional properties and characteristics to determining the durability or how well they respond to the test of time are cleavage, molecular bonds, stability, treatments, and enhancements among other things.

Let’s take a look at some of the most important determining factors for the durability of a gemstone.

Cleavage

The gemstone cleavage is its ability to break cleanly along a certain distinct line. This depends on the crystalline structure that the different kinds of gemstones have. Gemstones can have either a perfect cleavage, a completely non-existent one, or anywhere in between the two extremes.

Diamonds have perfect gemstone cleavage. It means that a diamond can be split into two pieces by striking it at the perfect spot even with a softer mineral. The cleavage is particularly important when it comes to the shaping and polishing of stones. A lack of knowledge about the cleavage of a gemstone can ruin even the hardest gemstones on the Mohs Scale.

Stability

The stability is based on how well the mineral can endure different conditions in the environment; such as pressure, chemicals, and temperatures. Some gemstones like the unheated amethyst can lose their natural color upon exposure to heat. Opals are minerals that are particularly susceptible to changes in temperature. They can even crack if there is a sudden temperature change. which indicates that they are not one of the most stable minerals.

A set of molecules
“DSC_2324b.jpg”by i(saw) e(saw) is licensed under CC BY-NC 2.0

Molecular Bonds

The crystalline structure or the molecular bonds of a gemstone are other important factors in determining overall durability. Some stones have a high rating on the Mohs Hardness Scale but their overall durability happens to be low because their molecular structure is not that strong. Jade happens to have a 7.0 rating on the Mohs Scale but the overall durability of the mineral is much more than that because it has a strong molecular structure.

Treatments & Enhancements

Several gemstones go through different processes of treatment when they are being refined. The processes involved are usually done to improve either the color or the overall integrity of the stone, based on how it is needed. The most common form of enhancement to gemstones is heat treatment. It can be used to affect the color of some gemstones that are susceptible to heat. The different treatments can have an impact on a mineral’s overall durability depending on the qualities of that particular stone.

Final Thoughts

It is important to be familiar with mineral durability if you have an interest in gemstones. Knowing this information will help you to find not only the most beautiful stones but also the ones that will stand the test of time.

Herkimer Diamonds: The Rare Form of Quartz

Herkimer DiamondsQuartz is a silicon mineral naturally found in crystalline form in all parts of the world. Even though they are excavated in the form of crystals, the specimens don’t have any noteworthy financial demand in the gem industry.

However, there is a rare form of quartz that has a different appearance from regular specimens, and subsequently enjoys great recognition among gem lovers and collectors.

This rare specimen of quartz is called the Herkimer Diamond. Yes, a quartz mineral denoted by the word ‘diamond’. But it is not a diamond so don’t get confused. We are going to clear up the origination of this name as well as many other aspects of this exceptional crystal in this article.

Why Herkimer?

These peculiar quartz specimens were first discovered in Herkimer County in the state of New York. Now, they are also mined in Arizona and globally, this particular mineral has been discovered in China, Norway, and Afghanistan.

The discovery of the Herkimer Diamond in the US doesn’t imply that it was found within the last two or three hundred years. Historical anecdotes suggest that Native Americans and early settlers discovered this special stone somewhere around the 15th century in water streams. Its peculiar double-edged appearance immediately caught the interest of Mohawk Indians. These Herkimer discoverers not only use it as an ornamental object but also employed it in different tools because of its pointed nature.  

Why Call it a ‘Diamond’?

The Herkimer gemstone is called ‘diamond’ because of its naturally developed faceting on both ends. The formation of this quartz crystal looks more attractive and has a bit of a diamond’s brilliance when it is polished. It is also said the people who originally discovered it thought of it as a diamond and from then on, the ‘diamond’ stuck to its name.

What’s the Difference between Regular Quartz and the Herkimer Diamonds?

Now it’s time to discuss the underlying reasons which make the Herkimer Diamond different from regular quartz crystals. Herkimer diamonds stand apart from other quartz crystals because of their double termination trait. Yes, these are the same characteristics that provide the crystals with facets on both ends. Quartz innately appears elongated because of its hexagonal structure. And in the case of the Herkimer Diamond, this elongation is more prominent due to the pointed (faceted) two ends of the stone.

How Double Termination Develops

Quartz is formed in and around rocks after millions of years of chemical and physical changes involving silicon and oxygen and affects its crystal formation. Herkimer crystals are also formed through this same process except that they don’t get in contact with the rock formation process. The environment in which Herkimer diamonds are produced provides enough room for them to get pure natural faceting on both ends.

Geological Occurrence of Herkimer Diamonds

dolomitic rock in Cirque_de_Mourèze France
Dolomitic rock in Cirque_de_Mourèze France. Wikipedia.

As mentioned earlier, quartz is geologically formed in a host rock called Dolostone formations. And this is the case for Herkimer Diamonds as well. These rock formations came into existence nearly 500 million years ago with the cavities from where most of the Herkimer Diamonds are mined from.

Properties of Herkimer Diamonds

Most of the physical properties of Herkimer Diamonds are like any other quartz specimen and they also exhibit a smoky appearance. However, the Herkimer diamond often contains liquid hydrocarbon inclusions which are not found in other excavated quartz crystals. Besides that, carbon dioxide gets trapped in its crystalline structure.

Solid inclusions for Herkimer diamonds are the same as regular quartz crystals which include dolomite, sphalerite, and pyrite. Minute quartz particles are also present in some Herkimer diamond specimens. The specific gravity and hardness of Herkimer diamonds also got the same value as any regular quartz crystal.

Mining of Herkimer Diamonds

Bucket Wheel Excavator
Bucket Wheel Excavator

The mining of the Herkimer diamond on a large commercial scale is done rarely. In most cases, enthusiasts try to mine them on their own. Small-scale mining is also feasible because it doesn’t need extensive and excavation that can only be carried out through specialized machinery.

Let’s have a look at the prevalent methods employed by gemstone buffs to mine Herkimer diamonds.

Break and Find Mining 

Enthusiasts find Dolostone rock formations and break them open with sledgehammers. Those who get lucky find some double-faceted quartz from the inside. It is important to note that Dolostone is not a soft rock specimen. Collectors have to work hard and long to smash these stones, which are also further reinforced because of the added layers of silica.  

Scavenging

Many people just go on hunting expeditions in quartz mines to find these intriguing gems. Searching the rubble of broken-down rocks is another way by which many collectors have succeeded in acquiring some tiny specimens.  

Mining after Cavity Prospecting

This is somewhat a commercial method employed by collectors to get to the large deposits of Herkimer diamonds. Large wedges and sledgehammers are used to drill through the quarry walls and floors to reach the Herkimer diamond-laden cavities present in Dolostone formations. This method is used to find the large deposits in a single mining location. One has to be extremely good with the use of tools for mining involved cavity prospecting.

An Ornamental Item

Fine Herkimer diamonds are not just confined to stone collections. They are also used as ornamental objects and can be used in a wide range of jewelry items. From bracelets to necklaces and earrings, they can fit into any jewelry piece since they are naturally found in many different shapes.

A good Mohs Hardness measurement also ensures that they provide better functionality as ornamental objects. This means these quartz crystals are resistant to scratching and other everyday abrasions. People who believe in metaphysical attributes of stones often possess Herkimer Diamonds for its different healing and mystical benefits. People who follow Chakra’s healing techniques also use this mineral for balancing the energies within the body.

Pyrite: The Mineral Known as the Gold Imposter

”Pyrite in its natural form"
Photo by PiLens – yayimages.com

Human fascination with gold is as ancient as the civilization itself. Throughout the timeline of history, this bright and yellow mineral has always been considered a precious and prized commodity. Such was the appeal and requisition for the mineral that people even tried to produce synthetically. It is often said that the foundation of modern chemistry was laid down with the attempts of producing gold in labs.

Due to its prized stature, gold is also often used to carry out fraud, directly or indirectly. For instance, its imitations are often sold as original to rip off uninformed consumers as many naturally occurring minerals resemble gold.

Pyrite is one such example that bears a resemblance to gold in its naturally occurring and refined states. For that reason, it is also called fool’s gold since people who can’t tell gold and pyrite apart can easily be scammed by the latter as the expensive precious metal. In this article, we are going to discuss pyrite and the methods that can be used to tell it apart from gold.

Pyrite: A Sulfide Mineral

Pyrite is one of the most common sulfide minerals in nature.  If one breaks down pyrite chemically, then a single molecule of pyrite is composed of one atom of iron and two sulfide ions. The natural form of pyrite displays a dull brass yellow color. However, it can be processed and furnished to give a bright metallic luster. This is the reason why it starts to look like a gold specimen, particularly to all those who are not expert in distinguishing different minerals.

Whether, it’s ingenious, sedimentary or metamorphic rock formations, small deposits of pyrite can be found in every geographic setting. This is the reason why pyrite is an inexpensive mineral and worth nothing when compared to gold.  It is important to mention that some traces of original gold can be found in some naturally occurring pyrite deposits though, but never enough to consider this element to be worth anything of value.  

Practical Uses of Pyrite

There are two notable practical uses of pyrite. Let’s take a look.

Pyrite as Sparking Material

Pyrite has been used as a sparking material for centuries. Sparking characteristic of the mineral is also the reason behind the name ‘pyrite’. The word is derived from a Greek word ‘pyre’, which means ‘fire’. With industrial processes getting modernized really fast, this use of pyrite has also been reduced. Nevertheless, it is still used in flintlock guns as a sparking material.

Production of Sulfur and Sulfuric Acid

These days, pyrite deposits are largely used to produce sulfur and sulfuric acid on a commercial level.

Use of Pyrite in Feng Shui Practice

Feng Shui is a thousands-year-old Chinese tradition of controlling the energies in the environment for a happier and content life. This ancient practice associates the energies emitting out of pyrite with wealth and abundance. The Feng Shui use of pyrite entails keeping it in the home as a decoration or wearing it in the form of a pedant.  

Differentiating Gold and Fool’s Gold  

Mineralogists often carry out destructive and non-destructive tests to distinguish apparently similar minerals. Several destructive and non-destructive tests are used to differentiate gold and pyrite. Destructive tests usually involve physical and chemical tests. Therefore, they are not used if there are strong chances that the given specimen is actual gold and not pyrite. Let’s have a look at all such tests used to tell the difference between actual gold and fool’s gold (pyrite).

Non-destructive tests

Color

The color of the naturally occurring specimen is another characteristic that can be used to tell gold and fool’s gold apart. Natural and unrefined gold specimen has bright yellow to golden tinge. In contrast, pyrite exhibits brassy tinge. Many naturally occurring gold specimens are often alloyed with silver deposits, giving the extracted piece a whitish yellow color.

Tarnish

Some minerals already have tarnish on their surface when they are found in nature. So, analyzing this feature can be used as one of the non-destructive tests. Naturally occurring gold flecks and lumps are usually untarnished and already bright. On the other hand, pyrite specimens often contain some sort of tarnish on their surface.

Shape

Gold and pyrite specimens can be differentiated on the basis of shape as well. However, this non-destructive test alone should not be used to differentiate the two because some of their naturally occurring crystalline specimens can exhibit a similar crystal habit. Otherwise, pyrite is usually found with angular edges, giving its specimen the shape of cube, pyritohedron or octahedron. In contrast, gold specimens are found in rounded shapes.

Striations

Many pyrites deposits are found with fine parallel striations on their surface. Striations are not present on gold.

Specific Gravity Test

The specific gravity (SC) of the pure gold specimen is 19.3 while pyrite has SC value of 5. Even the naturally occurring alloyed form of gold has specific gravity more than 5. So, this is another way to differentiate between gold and pyrite. Specific gravity is a simple lab test that can be carried out with a beaker and weighing machine.  

Destructive Tests

Hardness

The hardness of both minerals is also considerably different from each other. Gold and fool’s gold have a hardness of 2.5 and 6.0 on the Mohs scale respectively. Copper has a Mohs hardness of 3.0. This means gold specimen can’t scratch copper. However, fool’s gold or pyrite can do that.

Streak Test

Streak test of minerals entails observing their color in finely powdered form. Gold streaks appear yellow, whereas fool’s gold exhibits greenish black tinge in its amorphous form.

Ductility

Gold is extremely ductile. It can easily be bent into shapes even with a pin or soft wooden stick. On the other hand, pyrite either resists or gets broken into pieces upon the application of pressure.

Sectility

Sectility is a physical property of any material to be cut into pieces. Gold has an extremely good value of sectility as compared to fool’s gold. This implies that even the small pieces of gold can be cut into additional pieces. However, small pyrite pieces can’t be further minimized.