An Article In Meteorite-Times Magazine
by Robert Verish

Update on "Slag Meteor-wrongs"

Most "Slag Meteor-wrongs" are composed of Ferrosilicon alloys called Ferro-manganese and Ferro-chrome by the steel-making industry, but mineralogists prefer the term "synthetic silicides".


Well, two years have already gone by since my last article about "slag meteor-wrongs" was published here on and, if anything, even more of this particular type of "wanna-be meteorite" has come out-of-the-woodwork, as a steady stream of meteor-wrongs continue to appear on the internet and in the meteorite market. And, if this can be attributed to an ever-increasing popularity in meteorite collecting and to the publicity by the media of this recent spate of bolides, then we can expect to see even more "finders" coming forward with this kind of meteor-wrong.

With that possibility in mind, I felt it was necessary to update my earlier article and to clarify certain terminology in order to more readily identify this particular kind of meteor-wrong and to help "stem the tide" of its appearance in the meteorite market.

To be clear, the meteor-wrong being discussed here is a variety of man-made rock that goes by the industrial trade name of "Ferro-manganese" which is a by-product from a blast furnace and is primarily used as an oxidizer in the production of low-carbon steel. Another similar material, but which is processed differently and is used in the production of a different kind of steel, has the trade name, "Ferro-chrome".

Both of these materials (as well as, a wide variety of similar material) fall under the general heading of "ferro alloy". But don't think of this material as being a metal, because to the trained-eye of a petrologist Ferro-silicon is actually a rock composed of a variety of crystalline minerals that are known by the name, "silicides".
To be more specific, the specimen depicted in the above image was sent to Tim McCoy and colleagues at Smithsonian Institute, where under testing by X-ray diffraction, it was determined that this rock was composed of "manganese silicide".

Now here's another story about how a specimen that was found in Tucson came to be examined by me in June of 2009. In my image below, the woman holding the "manganese silicide" specimen is from San Bernardino, California, but she says that this specimen was found by her nephew in Tucson, Arizona, and she was helping him get it identified.

In any case, since there were two other people from the San Bernardino area that wanted me to examine their "meteorites" [meteor-wrongs] , I arranged that all of us would meet together at the same time. Not only did this save me alot of travel time, but it proved to be fortuitous, because one of the people at the meeting was a retired employee from the Fontana Steel Mill, and he readily identified the womans rock as being "ferro-manganese" (his own words). This unsolicited coroborration proved very satisfying to me because she was having a hard time accepting that her nephew's rock was actually slag.


Specimen of ferro-manganese supposedly from Tucson, brought to me by a lady who lives in San Bernardino.


Specimen of ferro-manganese (manganese silicide) from a lady who lives in San Bernardino.

Now regarding the term "FERROCHROMANGANESE": since the process that produces chromium-steel would never introduce manganese into the alloy, there is no commercial use for such a material. Hence, there is no purposeful production of this man-made material. In fact, a Google search of this term, only results in one single reference, as well as, the handful of webpages that link to this single reference. Unfortunately it was my prior article and the IMCA webpage titled "Hot Rocks" that were those webpages that linked to that "single reference" of "ferrochromanganese" and that promoted its usage and brought about its appearance on the internet.
Since this term appears to be an invention to cover a variety of ferro-alloy meteor-wrongs, as well as, being difficult for the general public to pronounce, it is recommended that its usage be discontinued, and that it be replaced by, either a more general term such as, "ferro alloy", or a more specific term such as, "silico-manganese", if the variety of ferro-alloy is known.


Specimens of ferro-manganese from a single locality (a short section of a railway bed) - even after a mild cleaning they still retain a black, powdery crust composed of manganese dioxide (MnO2).


Tarnish developes on unprotected cut surface (right-side, left-side was protected) after just a couple weeks of exposure outdoors. The similarity of this man-made mineral to naturally occuring arsenopyrite is more than just a coincidence. [See in the "References: ", below, for the Slag piles contamination report.]

It didn't take too much detective work to track down the source of the slag used by the railway in their track-ballast. Nearly all of this slag comes from two huge slag heaps in Fontana (California) and was purposely dumped there by the Kaiser Steel Co.
[See the "References: ", below, for the Fontana Steel Mill.]


The black-tarnished, manganese-rich rock, which is here termed, "ferro manganese", originated from a slag-heap at the former Kaiser Steel Mill in Fontana, California. This particular kind of slag is not produced in "steel furnaces", but was formed in the older "iron blast furnaces".

Of course, none of this explains how these man-made rocks are getting into the natural environment. The finders of these meteor-wrongs may never get a good answer to that question.


Bob's Findings - article titled, New Source for "Slag Meteor-wrongs", in - July 2007.

Silicides, in Fulgerutes and Ferrosilicon:
Unusual Compounds Formed under Reducing Conditions in Nature and Industry

Ferro manganese slag:

Import/Export - File for the International Uniform Chemical Information Database.
The ferromanganese slag is a lumpy, odor-free material with a green/brown coloured surface which can turn brown/black during storage:
** The analysis of the slag will vary based on the ore used in
** the production of HC FeMn, on the basicity used in the
** furnace operation and the slag adjustment materials used.
** Typical analysis:
** Mn 26-32%, present as MnO (33-42%)
** SiO2 approx. 24%
** Al2O3 max 12%, typ. 10%
** CaO approx. 18%
** MgO approx. 3%
** K2O max 2.5%
** P typ. 0.02%
** The slag is not a simple mixture of the listed elements/oxides as the elements are bound in a complex oxide/silicate structure. It would therefore be incorrect to report the elements/oxides as impurities.

Hot Rocks. Meteorite identification. Meteor-wrongs on the web ...

FERRO MANGANESE The interior "looks like" a natural sulfide mineral with a highly specular, metallic luster. But it is not a metal. It is actually a rock. It is composed of minerals termed, "Fe-Mn silicides"...

Ferrochrome lumps.

These are walnut-sized lumps of ferrochrome from a scrap metal shop in southern California.

Iron and Steel Slag: "Slag ain't Slag!"

File Format: PDF/Adobe Acrobat - View as HTML
Iron Slag = Blast Furnace Slag. Air-cooled. Granulated. Pelletized.
Steel Slag = Steel Furnace Slag. Bottom Boiler Slag ...

Why Control Sulfur Content?

How manganese controls sulfur content in steel processing.

Slag comes from the production of steel:

Accounting for 60% of the world's total output of crude steel, the Basic Oxygen Steelmaking (BOS) process is the dominant steelmaking technology.


The mineral, Pyrolusite, is the most important ore mineral of MANGANESE, forms dark gray to black coatings, crusts, columnar or granular masses, and rare crystals (polianite) that have one perfect cleavage. Pyrolusite results from alteration of MANGANITE and other manganese minerals.
About 95% of the world's annual production of manganese is used by the iron and steel industry to purify iron and to make alloys. Manganese is added to iron because it reduces iron oxide to form manganese oxide, which dissolves well in molten slag and is easily separated from the iron.


Definition and Much More from


Definition, Synonyms and Much More from


Definition, Synonyms and Much More from

Cast iron:

Definition, Synonyms and Much More from

Pig iron:

Definition, Synonyms and Much More from


is sometimes also referred to as specular pig iron, Spiegel iron, just Spiegel. Definition, Synonyms and Much More from

Specular pig iron:

[Definitions from] A fusible white cast iron containing a large amount of carbon (from three and a half to six per cent) and some manganese. When the manganese reaches twenty-five per cent and upwards it has a granular structure, and constitutes the alloy ferro manganese, largely used in the manufacture of Bessemer steel. Called also specular pig iron, spiegel, and spiegeleisen.
Webster's Revised Unabridged Dictionary, 1996, 1998 MICRA, Inc.

Blast Furnace Slag - Material Description:

User Guidelines for Waste and By-Product Materials Use in Pavement Construction.

Ferrochrome lumps.

These are walnut-sized lumps of ferrochrome from a scrap metal shop in southern California.


This is one of the most commonly misidentified 'meteorites' in Oregon.

U.S. GEOLOGICAL SURVEY Scientific Investigations Report 2004-5090.

Metallurgical Slag Particles in Accumulated Bed Sediments of Lake Roosevelt, Washington.

Fontana Steel Mill - slag piles

The East Slag Pile Landfill Area covers approximately 90 acres in the eastern half of the southern part of former steel mill. This area consists of a mound ... - 56k - Cached -

EnviroStor Database

The original Kaiser Steel Mill facility was located on 1200 acres in Fontana. The facility was a former integrated steel production plant that the Kaiser ...

Fontana Steel Mill - slag piles

One man's toxic waste is another man's meteor-wrong! Everything you didn't want to know about ...
East Slag Pile Landfill. Former Kaiser Steel Mill Site. Fontana, California. Project No. ..... Slag Pile itself consisted mostly of iron and steel slag, ... - -

[PDF] NegativeDeclaration

File Format: PDF/Adobe Acrobat - View as HTML
the former Kaiser Steel Mill site in Fontana, California. ... was used to store slag, a by-product of iron and steel production, from the ...

Source for Ni (nickel) in slag.

[meteorite-list] EBAY Slag for sale.

Other SIMILAR links:

My previous articles can be found *HERE*

For for more information, please contact me by email: Bolide*chaser