Difference between revisions of "Microcline"
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[[File:20.268-SC39857.jpg|thumb|Microcline pendant<br>MFA Acc. #: 20.268]] | [[File:20.268-SC39857.jpg|thumb|Microcline pendant<br>MFA Acc. #: 20.268]] | ||
== Description == | == Description == | ||
| − | + | [[File:Feldsparemr1.jpg|thumb|Microcline (potassium feldspar)]] | |
A variety of potash | A variety of potash | ||
[[feldspar|feldspar]] that is chemically identical to | [[feldspar|feldspar]] that is chemically identical to | ||
| − | [[orthoclase|orthoclase]]. However microcline has a triclinic crystalline system while orthoclase has a monoclinic crystalline system. Under a polarizing microscope, microcline displays a minute multiple twinning that forms a grating-like pattern. Amazon stone, or | + | [[orthoclase|orthoclase]]. However microcline has a triclinic crystalline system while orthoclase has a monoclinic crystalline system. Microcline may be clear, white, pale-yellow, brick-red, or green. Under a polarizing microscope, microcline displays a minute multiple twinning that forms a grating-like pattern. Amazon stone, or |
[[amazonite|amazonite]], is a green microcline that has been used since antiquity for decorative items. Microcline is used in making glass, porcelain, and enamel. Major deposits are found in Italy (Baveno), Norway (Kragerø), Madagascar, Russia (the Urals), and the U.S. (Colorado). | [[amazonite|amazonite]], is a green microcline that has been used since antiquity for decorative items. Microcline is used in making glass, porcelain, and enamel. Major deposits are found in Italy (Baveno), Norway (Kragerø), Madagascar, Russia (the Urals), and the U.S. (Colorado). | ||
| − | |||
== Synonyms and Related Terms == | == Synonyms and Related Terms == | ||
| − | + | [[File:Microcline.jpg|thumb|albite twinning under polarized light; credit Eurico Zimbres]] | |
amazonite; feldspar; microclina (Esp., Port.); microklien (Ned.) | amazonite; feldspar; microclina (Esp., Port.); microklien (Ned.) | ||
| − | + | [[[SliderGallery rightalign|Microcline, PMA.TIF~FTIR (PMA)|Microcline IR-ATR RRUFF R050150.png~IR-ATR (RRUFF)|Microcline Raman RRUFF R050150.png~Raman (RRUFF)|microclineRS.jpg~Raman (RASMIN)]]] | |
| − | [[[SliderGallery rightalign|Microcline, PMA.TIF~FTIR (PMA)|microclineRS.jpg~Raman]]] | ||
| − | |||
== Physical and Chemical Properties == | == Physical and Chemical Properties == | ||
| − | Color= colorless Crystal system = triclinic, | + | * Color= colorless, white, pale-yellow, brick-red, or green |
| + | * Crystal system = triclinic, exhibits albite twinning (grating pattern) | ||
| + | * Cleavage = perfect in one direction and good in another | ||
| + | * Fracture = uneven | ||
| + | * Luster = vitreous | ||
| + | * Streak = white | ||
| + | * Fluorescence = generally inert; may show weak yellowish green in LW | ||
| + | * Pleochroism = absent | ||
{| class="wikitable" | {| class="wikitable" | ||
| Line 22: | Line 26: | ||
! scope="row"| Composition | ! scope="row"| Composition | ||
| K2O-Al2O3-6SiO2 | | K2O-Al2O3-6SiO2 | ||
| + | |- | ||
| + | ! scope="row"| Mohs Hardness | ||
| + | | 6.0-6.5 | ||
| + | |- | ||
| + | ! scope="row"| Density | ||
| + | | 2.5-2.6 g/ml | ||
| + | |- | ||
| + | ! scope="row"| Refractive index | ||
| + | | 1.514- 1.539 | ||
| + | |- | ||
| + | ! scope="row"| Birefringence | ||
| + | | undetectable to 0.007 | ||
|} | |} | ||
| − | |||
== Resources and Citations == | == Resources and Citations == | ||
| − | + | * Gem Identification Lab Manual, Gemological Institute of America, 2016. | |
* G.S.Brady, ''Materials Handbook'', McGraw-Hill Book Co., New York, 1971 Comment: p. 316 | * G.S.Brady, ''Materials Handbook'', McGraw-Hill Book Co., New York, 1971 Comment: p. 316 | ||
| − | |||
* Jack Odgen, ''Jewellery of the Ancient World'', Rizzoli International Publications Inc., New York City, 1982 | * Jack Odgen, ''Jewellery of the Ancient World'', Rizzoli International Publications Inc., New York City, 1982 | ||
| − | |||
* ''Encyclopedia Britannica'', http://www.britannica.com Comment: "microcline" [Accessed March 4, 2002] | * ''Encyclopedia Britannica'', http://www.britannica.com Comment: "microcline" [Accessed March 4, 2002] | ||
| − | |||
* ''Ancient Egyptian Materials and Technologies'', Paul Nicholson, Ian Shaw (eds.), Cambridge University Press, Cambridge, 2000 Comment: B.Aston, J.Harrell, I.Shaw, "Stone" p. 21-22. | * ''Ancient Egyptian Materials and Technologies'', Paul Nicholson, Ian Shaw (eds.), Cambridge University Press, Cambridge, 2000 Comment: B.Aston, J.Harrell, I.Shaw, "Stone" p. 21-22. | ||
| − | + | * Wikipedia: [https://en.wikipedia.org/wiki/Microcline Microcline] (Accessed Sept. 10, 2005 and Dec 2022) | |
| − | * Wikipedia: | ||
| − | |||
* ''Van Nostrand's Scientific Encyclopedia'', Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976 | * ''Van Nostrand's Scientific Encyclopedia'', Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976 | ||
Latest revision as of 12:21, 19 December 2022
Description
A variety of potash Feldspar that is chemically identical to Orthoclase. However microcline has a triclinic crystalline system while orthoclase has a monoclinic crystalline system. Microcline may be clear, white, pale-yellow, brick-red, or green. Under a polarizing microscope, microcline displays a minute multiple twinning that forms a grating-like pattern. Amazon stone, or Amazonite, is a green microcline that has been used since antiquity for decorative items. Microcline is used in making glass, porcelain, and enamel. Major deposits are found in Italy (Baveno), Norway (Kragerø), Madagascar, Russia (the Urals), and the U.S. (Colorado).
Synonyms and Related Terms
amazonite; feldspar; microclina (Esp., Port.); microklien (Ned.)
Physical and Chemical Properties
- Color= colorless, white, pale-yellow, brick-red, or green
- Crystal system = triclinic, exhibits albite twinning (grating pattern)
- Cleavage = perfect in one direction and good in another
- Fracture = uneven
- Luster = vitreous
- Streak = white
- Fluorescence = generally inert; may show weak yellowish green in LW
- Pleochroism = absent
| Composition | K2O-Al2O3-6SiO2 |
|---|---|
| Mohs Hardness | 6.0-6.5 |
| Density | 2.5-2.6 g/ml |
| Refractive index | 1.514- 1.539 |
| Birefringence | undetectable to 0.007 |
Resources and Citations
- Gem Identification Lab Manual, Gemological Institute of America, 2016.
- G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 316
- Jack Odgen, Jewellery of the Ancient World, Rizzoli International Publications Inc., New York City, 1982
- Encyclopedia Britannica, http://www.britannica.com Comment: "microcline" [Accessed March 4, 2002]
- Ancient Egyptian Materials and Technologies, Paul Nicholson, Ian Shaw (eds.), Cambridge University Press, Cambridge, 2000 Comment: B.Aston, J.Harrell, I.Shaw, "Stone" p. 21-22.
- Wikipedia: Microcline (Accessed Sept. 10, 2005 and Dec 2022)
- Van Nostrand's Scientific Encyclopedia, Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976