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Miscellaneous Information - Ammolite and Ammonite
Ammolite ~~ Ammonite ~~ Unearthed ~~ Misc Info ~~ Gem Stones ~~ Lore ~~ Rockhounds
This page has lots of various information about ammolite:
Ammonite vs Ammolite
Other Names seen for Ammolite
Look-Alikes
Hardness
Composition
Aragonite
Structure
Diffraction vs Refraction
Black Lines
Gemstone Status / History
Location
Creation
Mining
Blackhorse Mine
Ammonite vs Ammolite
When a fossil is intact and continues to look like an ammonite shell, it is called an ammonite, even when the outer surface is beautiful gem ammolite. There are strict Canadian laws that prevent the destruction of these intact fossils.
When there is no recognizable fossil, just the gem ammolite, then the term ammolite is used. This ammolite can be left on large pieces of host rock as specimens or hand samples or can be finished off for use in jewelry.
Other Names seen for Ammolite
Korite, Calcentine, Opalescent Aragonite, Gem Ammonite, Aapoak or Aapok (Blackfoot), Iniskim (Blackfoot - select pieces that can be imagined to resemble a buffalo), Kirin Stone (Eastern mythical beast with scales), Alberta Opal (a misleading misnomer), Alberta Gem, Ammonite Shell.
During the development phases of ammolite, each company was trying to brand their process of creating a gemstone, thus some of the various names. After the CIBJO granted ammolite gem status in 1981, more people were calling the gem ammolite. In 1998, Korite chose not to renew their Canadian copyright on the term ammolite, clearing the way for its open use. Ammolite is the prevailing term used to refer to the gemstone today.
Auroralite™ is a name being applied by Aurora Canadian Jewellery to their mosaic ammolite gemstones.
Look-Alikes
Natural Stones - Some people compare the colors of Canadian Ammolite to that of Australian Black Opal or Mexican Fire Agate. While all three possess similar colors displays, they are each quite different. Once you have seen each of these three gems, you will not mistake one for the other.
There is also an Ethiopian Opal. This is the only natural stone that I have seen that I think gives the colors and liquid feel of ammolite.
There are also ammonite fossils throughout the world with some preserved nacre on them. And there is a limestone/marble called lumachelle or lumachella or fire marble that has fossilized mollusk shells embedded in it. The fossilized shells give it a brilliant iridescence and color-play. While these things remind you of ammolite, it is just not the same thing.
Dichroic Glass - a man-made product and an art form unto itself, I have never seen anyone try to pass off dichroic glass as ammolite. However, there are a few colors in dichroic glass that will remind you of ammolite if you ever see them. Specifically there is a dark purple dichroic that would be a purple ammolite lover’s dream and there is a dichroic color/pattern called ammonite fire that has wonderful reds/oranges with greens flashing out.
Fakes (aka Faux) - as with other expensive and rare gems, people use other material to simulate the look of ammolite. There is nothing wrong with this as long as it is clearly marketed as Faux Ammolite. While I have not seen any of the faux products yet, the pictures I have seen have made a good stab at simulating ammolite. The ones I know of are made from clay and have a clear shiny layer on the top. I can’t imagine that they have the iridescence or color play of a real ammolite, but if I get to see one, I’ll let you know.
Hardness
Ammolite ranges from 4 to 8 on the Mohs scale. Natural ammolite is normally about 4 on the scale. Protective quartz caps raise this to 7. Protective synthetic spinel caps increase the hardness to 8.
Composition
97% aragonite, 1% iron, 1% silica, 1% trace minerals such as titanium, copper, chromium, magnesium, manganese, aluminum, barium, silicon, strontium, and vanadium.
Aragonite
Aragonite, ammolite, pearls, and TUMS are all made from the same mineral: calcium carbonate.
Aragonite is a naturally occurring mineral with a vitreous luster. It is found in limestone caves and near hot springs and geysers. Aragonite and conchiolin are also secreted by most bivalve marine animals, to create their shells. The pearly luster and iridescence found on abalone shells and mother-of-pearl (also called nacre) are due to aragonite. Pearls are created when oysters coat an irritant with aragonite and conchiolin.
From what I have read, it is the crystal structure that makes aragonite separate and distinct from other forms of calcium carbonate. Calcite is a stable form of calcium carbonate. Aragoite is not a stable form. To use ammolite in jewelry, most must be stabilized, so that the layers will not flake off over time. Ammolite used as a display specimen may be coated with a UV protectant, which may yellow over time. Untreated ammolite left exposed to the elements (sun, snow, rain, heat, etc.) over time may decay and disintegrate.
Structure
Aragonite crystals form into thin scales and/or layers. Layers of different thickness build up, conchiolin may be present, and trace elements may be interspersed. Light hits the layers and is diffracted, creating the various colors of the rainbow. Color seen and intensity of that color will depend on what Mother Nature put in the particular mix.
Based on my experience with my first stone, it is randomly overlapping layers that cause the spectrochromatic shifts of color. Because different edges of scales at the lower levels peek out at different places, as you turned the stone, the light diffraction changes and the colors change. On mine, the stone would change from reds & greens to blues & oranges to yellow & greens. However, the person that set it into a ring broke the back and when the layers were ground down to repair the stone, the color shifts were lost, but I could see and appreciate the layers underneath that had been causing the other colors to appear.
I have read that it is diffraction (as opposed to refraction), that causes the iridescent colors seen in ammolite. From scientific sources - light diffraction and the resulting interference patterns produce -
~ red, when the stacks of scales/layers are thick and ordered
~ green, when the stacks of scales/layers are thinner and less ordered
~ blue, when the stacks of scales/layers are very thin and have no order
Lapidaries tell me that blue normally occurs in a lower layer than red and you have to grind off the red to get to an even layer for a gem. Lapidaries must be experienced and artistic enough to know just how far to polish into the layers of ammolite, to achieve the best the stone has to offer - sometimes even leaving an uneven surface in order to preserve the wonderful patterns in the stone.
Diffraction vs Refraction
Most gemstones refract light - they bend the light wave as it passes through the stone. This is similar to what happens when light passes through a prism.
The thin, overlapping layers of aragonite in ammolite diffract light - changing the direction and intensity of the light wave and creating interference patterns.
I can’t explain the differences in any greater detail, but I note the difference here because people that believe in ammolite for its metaphysical, spritual, or feng-shui aspects talk about feeling the energy of the stone. I therefore thought it interesting that ammolite is actually changing the nature of the light wave, which is associated with color and energy in these belief structures.
Black Lines
In many stones, black outlines the colors. These lines may be thin or thick and may add to or detract from the pattern. From what I have read, I think these lines are limonite, a natural iron oxide.
Gemstone Status / History
The interest of a handful of people in the 1970’s led to this gem becoming a commercial success. Information about the various people can be found in Donna Barnson’s book, Ammolite 2. Two of the people only have a passing mention in her book however, Dr. Wayne Bamber and Tom McArthur. Santo Carbone had been working with Dr. Bamber to create a stable ammolite gemstone. He introduced Bamber and McArthur in 1974. Tom McArthur owned a jewelry store. In 1971 he had seen the ammolite created by Charbonneau (Charbonneau coined the word ammolite in 1967) but found it to be unstable. He was interested to see the stone that Dr. Wayne Bamber and Santo Carbone had developed using "crush" layer material (dragonskin) as opposed to the sheet material that Charbonneau had used. The crazing in the "crush" material stopped the cleaving of the ammolite and made it stable.
Carbone was an expert in thin section techniques for microscopic examination of geological materials. Bamber was an expert in geological features and in studying the lay of the land to select locations that would contain ammonites. McArthur’s expertise was in gemology and the requirements of the jewelry trade. While the initial plan was for the three of them to create a company, Carbone was having family issues and decided to move away from the area. Bamber bought out the fruits of his and Carbone’s efforts to date and Bamer and McArthur formed a new company in 1975 (Calgary’s Centennial) called Calcentine. Bamber taught McArthur the thin section techniques required to create ammolite triplets and both worked towards their goal of creating a stable gemstone that would reliably meet the requirements of the jewelry trade. They started discussions with Richard Liddicoat, Jr. at the Gemological Institute of America in 1976 and received good press in the GIA’s summer 1977 publication which can be downloaded from the G&G archive (summer_1977.pdf - pg 26 of 34 within the pdf file, within the topic - "Developments & Highlights at GIA’s Lab in New York", titled "A New Jewelry Item").
Calcentine sought to work with the Kormos family and obtain mining rights to their land. The Kormos family decided to mine the area themselves. They did not know how to create the gemstones though, so they eventually combined forces with Santo Carbone, who had returned to the area. Their company did not thrive and eventually the Kormos family was bought out by Rene M. Vandervelde. Canadian Korite Gems Ltd. called their stone Korite and used a synthetic spinel cap. It is reported that Korite was very aggressive at knocking out all potential competition - using both fair and unfair methods. At one point, Calcentine lost their sales representative, the sample line in his possession, and all of the information and contacts he was supposed to be bringing back from a Japenese trade show to Korite. Calcentine reported losing jewelry store customers to Korite - by Korite infringing on the Calcentine trademark by passing their gems off as Calcentine; by Korite supplying goods on consignment (reported to be an illegal practice in Canada when used to steal customers from your competitors); and later by Korite refusing to do business with any store that would do business with McArthur. Canadian Korite Gems Ltd later morphed to Korite Minerals Ltd, which then morphed to the Korite International that exists today.
The first pit mining for the gem was not done until 1978. Red tape abounded as the Alberta government decided how to regulate mining for ammonite. Players other than Korite had great difficulty obtaining mining claims. The biggest producer of ammolite to date has been Korite.
Ammolite was recognized as a semi-precious gemstone by The International Commission Of Colored Gemstones (CIBJO) in 1981. It was upgraded to a precious gemstone in 2002. There are those that consider precious vs semi-precious to be a passe type of classification. No one however disputes that ammolite is a rare gemstone. Like all gemstones, just because it is genuine, it does not follow that it is a gem. You can find more information on what distinguishes gem ammolite from genuine ammmolite in the section Grading and Valuing Ammolite.
Location
Ammonite fossils are found worldwide. Ammonite fossils with lovely colors presumably coming from preserved shell are also found in various places around the world. But richly colored, true gem ammolite has only been found in the Bearpaw Shale formation of Canada and the United States. The largest mining operations have been centered in southern Alberta, Canada, along the St. Mary river.
Creation
The Bearpaw Sea existed approximately 75 million years ago. It was shallow, warm, and teemed with ammonite. Major volcano eruptions periodically caused thick layers of ash to settle through the water, killing the life trapped below it and sealing their remains in what became a mineral rich clay called bentonite.
In between eruptions, ammonites still died of other causes and settled to the bottom, to be buried by mineral-rich sediment brought into the sea from rivers flowing from the then young Rocky Mountains.
Time marched on - the glaciers came and went - the area got dramatically uplifted - the St. Mary river cut a swatch through the uplifted area - erosion occurred.
During all this time, the sediments and the trapped ammonites went through compaction (the weight of the stuff above it crushed it together), cementation (chemicals and minerals seeped into spaces, to glue everything together), things got buried deeper in the earth (increasing the temperature and pressure they were exposed to), and things got raised higher up towards the earth’s crust (decreasing the temperature and pressure they were exposed to). All of this, in combination with high concentrations of iron, magnesium, and other minerals in this particular region, somehow prevented aragonite from converting to a more stable form of calcium carbonate and gave it beautiful iridescent colors, creating ammolite.
Water and other forms of erosion uncovered these treasures thorough out the years. Pieces were often found in riverbeds. Looking deeper into the earth to find these treasures did not start until the 1980’s.
From what I have read, known deposits of ammolite are in 2 major layers of the earth in the Bearpaw formation. How far down those layers are depend on how close the Bearpaw Shale formation comes to the surface of the earth at any given point. Dragonskins come from the upper level while sheet patterns come from the lower level -
~ K Zone - "crush" - maybe 50 to 100 feet below the surface - Found in concretions (rounded mass of mineral found in sedimentary rock). The ammolite has been fractured, compacted, and naturally cemented with carbonate or conchiolin. The material in these concretions is also referred to as compacted or stable ammolite. I believe "rainbow stones" are more common in this layer. The material in this layer apparently does not split/cleave/flake/de-laminate and does not require a stabilization process prior to being polished.
~ Blue Zone - "sheet" - maybe 150 to 400 feet below the surface - Sometimes found in concretions. Usually found compressed with a thin layer of iron pyrite. The ammolite has few to no fractures, even though it has been compacted. Because it lies so deep, it is not as likely to be mined for as it is to be looked for as it is exposed in steep bluffs along the river. The material in this layer is also referred to as non-compacted or unstable ammolite. It will split/cleave/flake/de-laminate like mica. It must be stabilized prior to being polished in order to create a lasting gemstone.
Mining
Commercial collection of ammolite is done by surface collection and pit mining. Both are regulated by the Canadian government and both require licenses. My understanding is that the regulations protect intact ammonite fossils that are found, as well as private landowners, claim holders, commercial operations, and the environment. I believe each pit mine must be filled in and recovered before a new pit mine may be started.
Ammonite & ammolite may be found in concretions (rounded masses of mineral matter) or may be found "exposed". Exposed items are generally washed out during spring flooding, either left exposed on the banks of the river or washed into the river bed. Exposed ammolite that is left to weather too long is damaged by sun and frost and becomes too poor of a quality to be used as a gem.
Concretions are normally dug up in the pit mines. Excavators carefully dig trenches, removing the rock and dirt to look for these rounded shapes. The concretions are carefully set aside as they are found, to be cracked open and explored. Some have ammonite/ammolite - some do not.
Blackhorse Mine / roc-B-rocs
Blackhorse, a Blood Indian, owned and operated a coal mine on the Blood Indian reservation. It then passed to his grandsons. Their ability to mine ammonite and ammolite had been limited by a contract signed by a Blood Chief with Korite, which allowed Korite to mine the property. Korite’s contract terminated in Dec 2003. After that, two of the grandson’s and a great-grandson-in-law mined the property for ammonite and ammolite. Most of the ammolite on my site comes from the Blackhorse mine property.
Continue Reading
Ammolite ~~ Ammonite ~~ Unearthed ~~ Misc Info ~~ Gem Stones ~~ Lore ~~ Rockhounds
This page has lots of various information about ammolite:
Ammonite vs Ammolite
Other Names seen for Ammolite
Look-Alikes
Hardness
Composition
Aragonite
Structure
Diffraction vs Refraction
Black Lines
Gemstone Status / History
Location
Creation
Mining
Blackhorse Mine
Ammonite vs Ammolite
When a fossil is intact and continues to look like an ammonite shell, it is called an ammonite, even when the outer surface is beautiful gem ammolite. There are strict Canadian laws that prevent the destruction of these intact fossils.
When there is no recognizable fossil, just the gem ammolite, then the term ammolite is used. This ammolite can be left on large pieces of host rock as specimens or hand samples or can be finished off for use in jewelry.
Other Names seen for Ammolite
Korite, Calcentine, Opalescent Aragonite, Gem Ammonite, Aapoak or Aapok (Blackfoot), Iniskim (Blackfoot - select pieces that can be imagined to resemble a buffalo), Kirin Stone (Eastern mythical beast with scales), Alberta Opal (a misleading misnomer), Alberta Gem, Ammonite Shell.
During the development phases of ammolite, each company was trying to brand their process of creating a gemstone, thus some of the various names. After the CIBJO granted ammolite gem status in 1981, more people were calling the gem ammolite. In 1998, Korite chose not to renew their Canadian copyright on the term ammolite, clearing the way for its open use. Ammolite is the prevailing term used to refer to the gemstone today.
Auroralite™ is a name being applied by Aurora Canadian Jewellery to their mosaic ammolite gemstones.
Look-Alikes
Natural Stones - Some people compare the colors of Canadian Ammolite to that of Australian Black Opal or Mexican Fire Agate. While all three possess similar colors displays, they are each quite different. Once you have seen each of these three gems, you will not mistake one for the other.
There is also an Ethiopian Opal. This is the only natural stone that I have seen that I think gives the colors and liquid feel of ammolite.
There are also ammonite fossils throughout the world with some preserved nacre on them. And there is a limestone/marble called lumachelle or lumachella or fire marble that has fossilized mollusk shells embedded in it. The fossilized shells give it a brilliant iridescence and color-play. While these things remind you of ammolite, it is just not the same thing.
Dichroic Glass - a man-made product and an art form unto itself, I have never seen anyone try to pass off dichroic glass as ammolite. However, there are a few colors in dichroic glass that will remind you of ammolite if you ever see them. Specifically there is a dark purple dichroic that would be a purple ammolite lover’s dream and there is a dichroic color/pattern called ammonite fire that has wonderful reds/oranges with greens flashing out.
Fakes (aka Faux) - as with other expensive and rare gems, people use other material to simulate the look of ammolite. There is nothing wrong with this as long as it is clearly marketed as Faux Ammolite. While I have not seen any of the faux products yet, the pictures I have seen have made a good stab at simulating ammolite. The ones I know of are made from clay and have a clear shiny layer on the top. I can’t imagine that they have the iridescence or color play of a real ammolite, but if I get to see one, I’ll let you know.
Hardness
Ammolite ranges from 4 to 8 on the Mohs scale. Natural ammolite is normally about 4 on the scale. Protective quartz caps raise this to 7. Protective synthetic spinel caps increase the hardness to 8.
Composition
97% aragonite, 1% iron, 1% silica, 1% trace minerals such as titanium, copper, chromium, magnesium, manganese, aluminum, barium, silicon, strontium, and vanadium.
Aragonite
Aragonite, ammolite, pearls, and TUMS are all made from the same mineral: calcium carbonate.
Aragonite is a naturally occurring mineral with a vitreous luster. It is found in limestone caves and near hot springs and geysers. Aragonite and conchiolin are also secreted by most bivalve marine animals, to create their shells. The pearly luster and iridescence found on abalone shells and mother-of-pearl (also called nacre) are due to aragonite. Pearls are created when oysters coat an irritant with aragonite and conchiolin.
From what I have read, it is the crystal structure that makes aragonite separate and distinct from other forms of calcium carbonate. Calcite is a stable form of calcium carbonate. Aragoite is not a stable form. To use ammolite in jewelry, most must be stabilized, so that the layers will not flake off over time. Ammolite used as a display specimen may be coated with a UV protectant, which may yellow over time. Untreated ammolite left exposed to the elements (sun, snow, rain, heat, etc.) over time may decay and disintegrate.
Structure
Aragonite crystals form into thin scales and/or layers. Layers of different thickness build up, conchiolin may be present, and trace elements may be interspersed. Light hits the layers and is diffracted, creating the various colors of the rainbow. Color seen and intensity of that color will depend on what Mother Nature put in the particular mix.
Based on my experience with my first stone, it is randomly overlapping layers that cause the spectrochromatic shifts of color. Because different edges of scales at the lower levels peek out at different places, as you turned the stone, the light diffraction changes and the colors change. On mine, the stone would change from reds & greens to blues & oranges to yellow & greens. However, the person that set it into a ring broke the back and when the layers were ground down to repair the stone, the color shifts were lost, but I could see and appreciate the layers underneath that had been causing the other colors to appear.
I have read that it is diffraction (as opposed to refraction), that causes the iridescent colors seen in ammolite. From scientific sources - light diffraction and the resulting interference patterns produce -
~ red, when the stacks of scales/layers are thick and ordered
~ green, when the stacks of scales/layers are thinner and less ordered
~ blue, when the stacks of scales/layers are very thin and have no order
Lapidaries tell me that blue normally occurs in a lower layer than red and you have to grind off the red to get to an even layer for a gem. Lapidaries must be experienced and artistic enough to know just how far to polish into the layers of ammolite, to achieve the best the stone has to offer - sometimes even leaving an uneven surface in order to preserve the wonderful patterns in the stone.
Diffraction vs Refraction
Most gemstones refract light - they bend the light wave as it passes through the stone. This is similar to what happens when light passes through a prism.
The thin, overlapping layers of aragonite in ammolite diffract light - changing the direction and intensity of the light wave and creating interference patterns.
I can’t explain the differences in any greater detail, but I note the difference here because people that believe in ammolite for its metaphysical, spritual, or feng-shui aspects talk about feeling the energy of the stone. I therefore thought it interesting that ammolite is actually changing the nature of the light wave, which is associated with color and energy in these belief structures.
Black Lines
In many stones, black outlines the colors. These lines may be thin or thick and may add to or detract from the pattern. From what I have read, I think these lines are limonite, a natural iron oxide.
Gemstone Status / History
The interest of a handful of people in the 1970’s led to this gem becoming a commercial success. Information about the various people can be found in Donna Barnson’s book, Ammolite 2. Two of the people only have a passing mention in her book however, Dr. Wayne Bamber and Tom McArthur. Santo Carbone had been working with Dr. Bamber to create a stable ammolite gemstone. He introduced Bamber and McArthur in 1974. Tom McArthur owned a jewelry store. In 1971 he had seen the ammolite created by Charbonneau (Charbonneau coined the word ammolite in 1967) but found it to be unstable. He was interested to see the stone that Dr. Wayne Bamber and Santo Carbone had developed using "crush" layer material (dragonskin) as opposed to the sheet material that Charbonneau had used. The crazing in the "crush" material stopped the cleaving of the ammolite and made it stable.
Carbone was an expert in thin section techniques for microscopic examination of geological materials. Bamber was an expert in geological features and in studying the lay of the land to select locations that would contain ammonites. McArthur’s expertise was in gemology and the requirements of the jewelry trade. While the initial plan was for the three of them to create a company, Carbone was having family issues and decided to move away from the area. Bamber bought out the fruits of his and Carbone’s efforts to date and Bamer and McArthur formed a new company in 1975 (Calgary’s Centennial) called Calcentine. Bamber taught McArthur the thin section techniques required to create ammolite triplets and both worked towards their goal of creating a stable gemstone that would reliably meet the requirements of the jewelry trade. They started discussions with Richard Liddicoat, Jr. at the Gemological Institute of America in 1976 and received good press in the GIA’s summer 1977 publication which can be downloaded from the G&G archive (summer_1977.pdf - pg 26 of 34 within the pdf file, within the topic - "Developments & Highlights at GIA’s Lab in New York", titled "A New Jewelry Item").
Calcentine sought to work with the Kormos family and obtain mining rights to their land. The Kormos family decided to mine the area themselves. They did not know how to create the gemstones though, so they eventually combined forces with Santo Carbone, who had returned to the area. Their company did not thrive and eventually the Kormos family was bought out by Rene M. Vandervelde. Canadian Korite Gems Ltd. called their stone Korite and used a synthetic spinel cap. It is reported that Korite was very aggressive at knocking out all potential competition - using both fair and unfair methods. At one point, Calcentine lost their sales representative, the sample line in his possession, and all of the information and contacts he was supposed to be bringing back from a Japenese trade show to Korite. Calcentine reported losing jewelry store customers to Korite - by Korite infringing on the Calcentine trademark by passing their gems off as Calcentine; by Korite supplying goods on consignment (reported to be an illegal practice in Canada when used to steal customers from your competitors); and later by Korite refusing to do business with any store that would do business with McArthur. Canadian Korite Gems Ltd later morphed to Korite Minerals Ltd, which then morphed to the Korite International that exists today.
The first pit mining for the gem was not done until 1978. Red tape abounded as the Alberta government decided how to regulate mining for ammonite. Players other than Korite had great difficulty obtaining mining claims. The biggest producer of ammolite to date has been Korite.
Ammolite was recognized as a semi-precious gemstone by The International Commission Of Colored Gemstones (CIBJO) in 1981. It was upgraded to a precious gemstone in 2002. There are those that consider precious vs semi-precious to be a passe type of classification. No one however disputes that ammolite is a rare gemstone. Like all gemstones, just because it is genuine, it does not follow that it is a gem. You can find more information on what distinguishes gem ammolite from genuine ammmolite in the section Grading and Valuing Ammolite.
Location
Ammonite fossils are found worldwide. Ammonite fossils with lovely colors presumably coming from preserved shell are also found in various places around the world. But richly colored, true gem ammolite has only been found in the Bearpaw Shale formation of Canada and the United States. The largest mining operations have been centered in southern Alberta, Canada, along the St. Mary river.
Creation
The Bearpaw Sea existed approximately 75 million years ago. It was shallow, warm, and teemed with ammonite. Major volcano eruptions periodically caused thick layers of ash to settle through the water, killing the life trapped below it and sealing their remains in what became a mineral rich clay called bentonite.
In between eruptions, ammonites still died of other causes and settled to the bottom, to be buried by mineral-rich sediment brought into the sea from rivers flowing from the then young Rocky Mountains.
Time marched on - the glaciers came and went - the area got dramatically uplifted - the St. Mary river cut a swatch through the uplifted area - erosion occurred.
During all this time, the sediments and the trapped ammonites went through compaction (the weight of the stuff above it crushed it together), cementation (chemicals and minerals seeped into spaces, to glue everything together), things got buried deeper in the earth (increasing the temperature and pressure they were exposed to), and things got raised higher up towards the earth’s crust (decreasing the temperature and pressure they were exposed to). All of this, in combination with high concentrations of iron, magnesium, and other minerals in this particular region, somehow prevented aragonite from converting to a more stable form of calcium carbonate and gave it beautiful iridescent colors, creating ammolite.
Water and other forms of erosion uncovered these treasures thorough out the years. Pieces were often found in riverbeds. Looking deeper into the earth to find these treasures did not start until the 1980’s.
From what I have read, known deposits of ammolite are in 2 major layers of the earth in the Bearpaw formation. How far down those layers are depend on how close the Bearpaw Shale formation comes to the surface of the earth at any given point. Dragonskins come from the upper level while sheet patterns come from the lower level -
~ K Zone - "crush" - maybe 50 to 100 feet below the surface - Found in concretions (rounded mass of mineral found in sedimentary rock). The ammolite has been fractured, compacted, and naturally cemented with carbonate or conchiolin. The material in these concretions is also referred to as compacted or stable ammolite. I believe "rainbow stones" are more common in this layer. The material in this layer apparently does not split/cleave/flake/de-laminate and does not require a stabilization process prior to being polished.
~ Blue Zone - "sheet" - maybe 150 to 400 feet below the surface - Sometimes found in concretions. Usually found compressed with a thin layer of iron pyrite. The ammolite has few to no fractures, even though it has been compacted. Because it lies so deep, it is not as likely to be mined for as it is to be looked for as it is exposed in steep bluffs along the river. The material in this layer is also referred to as non-compacted or unstable ammolite. It will split/cleave/flake/de-laminate like mica. It must be stabilized prior to being polished in order to create a lasting gemstone.
Mining
Commercial collection of ammolite is done by surface collection and pit mining. Both are regulated by the Canadian government and both require licenses. My understanding is that the regulations protect intact ammonite fossils that are found, as well as private landowners, claim holders, commercial operations, and the environment. I believe each pit mine must be filled in and recovered before a new pit mine may be started.
Ammonite & ammolite may be found in concretions (rounded masses of mineral matter) or may be found "exposed". Exposed items are generally washed out during spring flooding, either left exposed on the banks of the river or washed into the river bed. Exposed ammolite that is left to weather too long is damaged by sun and frost and becomes too poor of a quality to be used as a gem.
Concretions are normally dug up in the pit mines. Excavators carefully dig trenches, removing the rock and dirt to look for these rounded shapes. The concretions are carefully set aside as they are found, to be cracked open and explored. Some have ammonite/ammolite - some do not.
Blackhorse Mine / roc-B-rocs
Blackhorse, a Blood Indian, owned and operated a coal mine on the Blood Indian reservation. It then passed to his grandsons. Their ability to mine ammonite and ammolite had been limited by a contract signed by a Blood Chief with Korite, which allowed Korite to mine the property. Korite’s contract terminated in Dec 2003. After that, two of the grandson’s and a great-grandson-in-law mined the property for ammonite and ammolite. Most of the ammolite on my site comes from the Blackhorse mine property.
Continue Reading
Ammolite ~~ Ammonite ~~ Unearthed ~~ Misc Info ~~ Gem Stones ~~ Lore ~~ Rockhounds