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1000 results for “silicatefondue”

  1. Repost from last year:
    I've seen sphene! (Sounds better than "the rock is tippsy with titanite")

    Centimeter-size black sphene (titanite) with apatite (dark brown) and orthoclase feldspar (light brown). Folding pocket knife for scale.

    From the Bancroft locality in Ontario, Canada. Grenville-aged (~1.2± billion years)

  2. Repost from last year:
    I've seen sphene! (Sounds better than "the rock is tippsy with titanite")

    Centimeter-size black sphene (titanite) with apatite (dark brown) and orthoclase feldspar (light brown). Folding pocket knife for scale.

    From the Bancroft locality in Ontario, Canada. Grenville-aged (~1.2± billion years)

    #MinCup25 #Titanite #Sphene #Bancroft #Ontario #Geology #Grenville

  3. Repost from last year:
    I've seen sphene! (Sounds better than "the rock is tippsy with titanite")

    Centimeter-size black sphene (titanite) with apatite (dark brown) and orthoclase feldspar (light brown). Folding pocket knife for scale.

    From the Bancroft locality in Ontario, Canada. Grenville-aged (~1.2± billion years)

    #MinCup25 #Titanite #Sphene #Bancroft #Ontario #Geology #Grenville

  4. Repost from last year:
    I've seen sphene! (Sounds better than "the rock is tippsy with titanite")

    Centimeter-size black sphene (titanite) with apatite (dark brown) and orthoclase feldspar (light brown). Folding pocket knife for scale.

    From the Bancroft locality in Ontario, Canada. Grenville-aged (~1.2± billion years)

    #MinCup25 #Titanite #Sphene #Bancroft #Ontario #Geology #Grenville

  5. Repost from last year:
    I've seen sphene! (Sounds better than "the rock is tippsy with titanite")

    Centimeter-size black sphene (titanite) with apatite (dark brown) and orthoclase feldspar (light brown). Folding pocket knife for scale.

    From the Bancroft locality in Ontario, Canada. Grenville-aged (~1.2± billion years)

    #MinCup25 #Titanite #Sphene #Bancroft #Ontario #Geology #Grenville

  6. Claudia Zahn @Adrenochrome
    has posted some astounding photos of over the last year. Below are two, but search the hashtag to see the whole collection!

  7. @Kaetchi I am not very knowledgeable about the Congo Copper Belt. Congo has very old copper-rich rocks (the Katanga Supergroup, 700-800 million year-old sediments). Malachite forms when underground water rich in CO2 reacts with existing copper minerals. Congo has not been glaciated for a long time, so that shallow-formed malachite is still preserved.

    Others who know more may pipe up or correct what I've written.

  8. @Kaetchi I am not very knowledgeable about the Congo Copper Belt. Congo has very old copper-rich rocks (the Katanga Supergroup, 700-800 million year-old sediments). Malachite forms when underground water rich in CO2 reacts with existing copper minerals. Congo has not been glaciated for a long time, so that shallow-formed malachite is still preserved.

    Others who know more may pipe up or correct what I've written.

    #CopperbeltProvince #Congo #Copper #Malachite

  9. @Kaetchi I am not very knowledgeable about the Congo Copper Belt. Congo has very old copper-rich rocks (the Katanga Supergroup, 700-800 million year-old sediments). Malachite forms when underground water rich in CO2 reacts with existing copper minerals. Congo has not been glaciated for a long time, so that shallow-formed malachite is still preserved.

    Others who know more may pipe up or correct what I've written.

    #CopperbeltProvince #Congo #Copper #Malachite

  10. @Kaetchi I am not very knowledgeable about the Congo Copper Belt. Congo has very old copper-rich rocks (the Katanga Supergroup, 700-800 million year-old sediments). Malachite forms when underground water rich in CO2 reacts with existing copper minerals. Congo has not been glaciated for a long time, so that shallow-formed malachite is still preserved.

    Others who know more may pipe up or correct what I've written.

    #CopperbeltProvince #Congo #Copper #Malachite

  11. can form in the oxidized supergene zone of copper-rich rocks. More carbon dioxide favors azurite over . Our atmosphere doesn't have enough CO2 (yet) to stabilize azurite, but malachite at the surface persists kinetically rather than convert to black copper oxide. Sulfur and other species can modify these relations.

    Hence copper roofs weather to green, not blue!

    Diagram from Kiselcva et al. (1992)

  12. #Azurite can form in the oxidized supergene zone of copper-rich rocks. More carbon dioxide favors azurite over #malachite. Our atmosphere doesn't have enough CO2 (yet) to stabilize azurite, but malachite at the surface persists kinetically rather than convert to black copper oxide. Sulfur and other species can modify these relations.

    Hence copper roofs weather to green, not blue!

    Diagram from Kiselcva et al. (1992)

    #MinCup25 #SupergeneEnrichment #Copper

  13. #Azurite can form in the oxidized supergene zone of copper-rich rocks. More carbon dioxide favors azurite over #malachite. Our atmosphere doesn't have enough CO2 (yet) to stabilize azurite, but malachite at the surface persists kinetically rather than convert to black copper oxide. Sulfur and other species can modify these relations.

    Hence copper roofs weather to green, not blue!

    Diagram from Kiselcva et al. (1992)

    #MinCup25 #SupergeneEnrichment #Copper

  14. #Azurite can form in the oxidized supergene zone of copper-rich rocks. More carbon dioxide favors azurite over #malachite. Our atmosphere doesn't have enough CO2 (yet) to stabilize azurite, but malachite at the surface persists kinetically rather than convert to black copper oxide. Sulfur and other species can modify these relations.

    Hence copper roofs weather to green, not blue!

    Diagram from Kiselcva et al. (1992)

    #MinCup25 #SupergeneEnrichment #Copper

  15. We're awash in structures this first half of the : five of the first sixteen, including two today.

    A and a

    Is tectosilirific a word?

    Fair enough, they are the major rock-forming minerals of the crust!

  16. from the Fish Canyon Tuff is essential to understanding the pace of events in the

    High potassium, quickly erupted and cooled, and old enough to have accumulated sufficient 40Ar from radioactive decay. These crystals calibrate neutron flux for 40Ar/39Ar dating. The 28.2 Ma age of the FCT sanidine has been fine-tuned using cycles of other ash beds in stable sedimentary basins.

    photo from MinDat.org by Dan Polhemus

  17. #Sanidine from the Fish Canyon Tuff is essential to understanding the pace of events in the #Cenozoic

    High potassium, quickly erupted and cooled, and old enough to have accumulated sufficient 40Ar from radioactive decay. These crystals calibrate neutron flux for 40Ar/39Ar dating. The 28.2 Ma age of the FCT sanidine has been fine-tuned using #Milankovitch cycles of other ash beds in stable sedimentary basins.

    photo from MinDat.org by Dan Polhemus

    #MinCup25 #Geochronology #DeepTime #Colorado

  18. #Sanidine from the Fish Canyon Tuff is essential to understanding the pace of events in the #Cenozoic

    High potassium, quickly erupted and cooled, and old enough to have accumulated sufficient 40Ar from radioactive decay. These crystals calibrate neutron flux for 40Ar/39Ar dating. The 28.2 Ma age of the FCT sanidine has been fine-tuned using #Milankovitch cycles of other ash beds in stable sedimentary basins.

    photo from MinDat.org by Dan Polhemus

    #MinCup25 #Geochronology #DeepTime #Colorado

  19. #Sanidine from the Fish Canyon Tuff is essential to understanding the pace of events in the #Cenozoic

    High potassium, quickly erupted and cooled, and old enough to have accumulated sufficient 40Ar from radioactive decay. These crystals calibrate neutron flux for 40Ar/39Ar dating. The 28.2 Ma age of the FCT sanidine has been fine-tuned using #Milankovitch cycles of other ash beds in stable sedimentary basins.

    photo from MinDat.org by Dan Polhemus

    #MinCup25 #Geochronology #DeepTime #Colorado

  20. #Sanidine from the Fish Canyon Tuff is essential to understanding the pace of events in the #Cenozoic

    High potassium, quickly erupted and cooled, and old enough to have accumulated sufficient 40Ar from radioactive decay. These crystals calibrate neutron flux for 40Ar/39Ar dating. The 28.2 Ma age of the FCT sanidine has been fine-tuned using #Milankovitch cycles of other ash beds in stable sedimentary basins.

    photo from MinDat.org by Dan Polhemus

    #MinCup25 #Geochronology #DeepTime #Colorado

  21. is used to make dental porcelain (or rather, leucite + glass from melting feldspar incongruently). Thiis is becuase it:
    is immune system compatible
    is machinable
    is fracture resistant with low porosity
    it doesn't easily stain or discolour
    and most importantly, its thermal expansion matches the metal anchor

    Image from: J.R. Mackert et al (1986)The effect of the leucite transformation on dental porcelain expansion, Dental Materials 2: 32-36

  22. #Leucite is used to make dental porcelain (or rather, leucite + glass from melting feldspar incongruently). Thiis is becuase it:
    is immune system compatible
    is machinable
    is fracture resistant with low porosity
    it doesn't easily stain or discolour
    and most importantly, its thermal expansion matches the metal anchor

    Image from: J.R. Mackert et al (1986)The effect of the leucite transformation on dental porcelain expansion, Dental Materials 2: 32-36

    #MinCup25 #Dentalimplant #Ceramic