Hyalophane
A variety of Microcline
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About Hyalophane
Formula:
(K,Ba)[Al(Si,Al)Si2O8]
Hardness:
6 - 6½
Crystal System:
Monoclinic
Name:
Named in 1855 by Wolfgang Sartorius von Waltershausen from the Greek ύαλος for "glass" and φαίνεσθαι, "to appear," in allusion to the transparency of its crystals. Dana (1892) listed hyalophane under a separate species heading for a feldspar containing two atoms of potassium to one atom of barium. In 1895, Barium-dominant feldspar was defined by Stens Anders Hjalmar Sjögren. Hyalophane is now a variety of microcline or orthoclase which contains substantial barium.
First Recorded Locality:
Celsian-Hyalophane Series, and the Hyalophane-Orthoclase Series (intermediate member).
Originally reported from Lengenbach Quarry, Im Feld (Imfeld; Feld; Fäld), Binn Valley, Wallis (Valais), Switzerland.
Originally reported from Lengenbach Quarry, Im Feld (Imfeld; Feld; Fäld), Binn Valley, Wallis (Valais), Switzerland.
Unique Identifiers
Mindat ID:
1960 (as Hyalophane)
2704 (as Microcline)
2704 (as Microcline)
Long-form identifier:
mindat:1:1:1960:2 (as Hyalophane)
mindat:1:1:2704:1 (as Microcline)
mindat:1:1:2704:1 (as Microcline)
IMA Classification of Hyalophane
'Grandfathered' (first described prior to 1959), Questionable
IMA status notes:
Intermediate member of a solid-solution series
Classification of Hyalophane
76.1.1.3
76 : TECTOSILICATES Al-Si Framework
1 : Al-Si Framework with Al-Si frameworks
76 : TECTOSILICATES Al-Si Framework
1 : Al-Si Framework with Al-Si frameworks
16.12.10
16 : Silicates Containing Aluminum and other Metals
12 : Aluminosilicates of Sr, Ba and Zn
16 : Silicates Containing Aluminum and other Metals
12 : Aluminosilicates of Sr, Ba and Zn
Physical Properties of Hyalophane
Hardness:
6 - 6½ on Mohs scale
Optical Data of Hyalophane
Type:
Biaxial (-)
RI values:
nα = 1.542 nβ = 1.545 nγ = 1.547
Max. Birefringence:
δ = 0.005
Based on recorded range of RI values above.
Based on recorded range of RI values above.
Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
Surface Relief:
None to Very Low
Relative to Canada balsam mounting medium (n ≈ 1.537).
Relative to Canada balsam mounting medium (n ≈ 1.537).
This shows the grain boundary and Becke line effect under plane-polarised
light, based on the contrast between this mineral's average refractive
index and the mounting medium. It does not take into account mineral
colouration.
In focus
Interference Figure:
This shows the idealized biaxial acute bisectrix (Bxa) interference figure
- the conoscopic view for a grain cut perpendicular to the acute bisectrix, using
this mineral's 2V. The two small white dots mark the melatopes - the points
where the two optic axes emerge - and are shown only when they fall within the
field of view. The coloured bands are isochromatics, and the dark bands are
isogyres.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
No measured or calculated 2V is on file for this mineral, so the value used here (78°) is estimated from its recorded refractive indices and optic sign, not from a direct 2V measurement.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
No measured or calculated 2V is on file for this mineral, so the value used here (78°) is estimated from its recorded refractive indices and optic sign, not from a direct 2V measurement.
Dispersion:
weak
Chemistry of Hyalophane
Mindat Formula:
(K,Ba)[Al(Si,Al)Si2O8]
Element Weights:
Common Impurities:
Ti,Na,Fe,Mg,Ca,H20
Crystallography of Hyalophane
Crystal System:
Monoclinic
Cell Parameters:
a = 8.52 Å, b = 12.95 Å, c = 7.14 Å
β = 116°
β = 116°
Ratio:
a:b:c = 0.658 : 1 : 0.551
Unit Cell V:
708.06 ų (Calculated from Unit Cell)
Crystal Structure
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Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
| 0000887 | Hyalophane | Viswanathan K, Kielhorn H M (1983) Al,Si distribution in a ternary (Ba,K,Na)-feldspar as determined by crystal structure refinement Celsian-rich American Mineralogist 68 122-124 |  | 1983 | Yugoslavia | 0 | 293 |
| 0009609 | Hyalophane | De Pieri R, Quareni S, Hall K M (1977) Refinement of the structures of low and high hyalophanes Acta Crystallographica B33 3073-3076 |  | 1977 | 0 | 293 | |
| 0009608 | Hyalophane | De Pieri R, Quareni S, Hall K M (1977) Refinement of the structures of low and high hyalophanes Acta Crystallographica B33 3073-3076 | | 1977 | 0 | 293 |
CIF Raw Data - click here to close
First Recorded Occurrence of Hyalophane
Synonyms of Hyalophane
Ba Feldspar (in part)
Other Language Names for Hyalophane
Common Associates
Associations Based on Photo Data:
| 23 photos of Hyalophane associated with Andradite | Ca3Fe3+2(SiO4)3 |
| 14 photos of Hyalophane associated with Willemite | Zn2SiO4 |
| 11 photos of Hyalophane associated with Rutile | TiO2 |
| 9 photos of Hyalophane associated with Celsian | Ba(Al2Si2O8) |
| 7 photos of Hyalophane associated with Margarosanite | Ca2PbSi3O9 |
| 6 photos of Hyalophane associated with 'Schefferite' | (Ca,Mn)(Mg,Fe,Mn)Si2O6 |
| 5 photos of Hyalophane associated with Calcite | CaCO3 |
| 5 photos of Hyalophane associated with Hendricksite | KZn3(Si3Al)O10(OH)2 |
| 5 photos of Hyalophane associated with Native Copper | Cu |
| 5 photos of Hyalophane associated with Quartz | SiO2 |
Radioactivity
Other Information
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Internet Links for Hyalophane
mindat.org URL:
https://www.mindat.org/min-1960.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Hyalophane
Reference List:
Gay, P.; Roy, N. N. (1968) The mineralogy of the potassium-barium feldspar series. III: Subsolidus relationships. Mineralogical Magazine and Journal of the Mineralogical Society, 36 (283). 914-932 doi:10.1180/minmag.1968.283.036.02
De Pieri, R., Quareni, S., Hall, K. M. (1977) Refinement of the structures of low and high hyalophanes. Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry, 33 (10) 3073-3076 doi:10.1107/s0567740877010280
Riley, Teal R., Bailey, D. Ken (2003) Barium-rich sanidine megacrysts from the West Eifel (Germany) Neues Jahrbuch für Mineralogie - Monatshefte, 2003 (1) 18-30 doi:10.1127/0028-3649/2003/2003-0018
Cressey, G. (2004) W.A. Deer, R.A. Howie, W.S. Wise and J. Zussman. Rock-Forming Minerals. Volume 4B. Second Edition. Framework Silicates: Silica Minerals, Feldspathoids and the Zeolites.
London (The Geological Society) 2004, xv + 982 pp. £125 (£62.50 to GSL members) ISBN 1-86239-144-0. Hardback. Mineralogical Magazine, 68 (5) 831-832 doi:10.1180/0680831pp.166-178
Localities for Hyalophane
Showing 161 localities.
symbol to view information about a locality.
The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and further information on this occurrence.
? - Indicates mineral may be doubtful at this locality.
- Good crystals or important locality for species.
- World class for species or very significant.
(TL) - Type Locality for a valid mineral species.
(FRL) - First Recorded Locality for everything else (eg varieties).
All localities listed without proper references should be considered as questionable.
Antarctica | |
| Plimer et al. (1983) |
Australia | |
| Birch BH Book |
| Segnit (1946) | |
| Langworthy et al. (1978) +2 other references |
| Taylor et al. (1983) |
| Graham (1978) |
| rumbleresources.com.au (2021) |
| minedex.dmirs.wa.gov.au (2020) +1 other reference |
| Vogt et al. (1987) |
Austria | |
| Taucher J. & Hollerer Ch. (2015) |
Azerbaijan | |
| Novgorodova M.I. (caspian Sea) |
Bosnia and Herzegovina | |
| Jurkoviae et al. (1993) +1 other reference |
Brazil | |
| Guarino et al. (2021) |
| Uchôa Filho et al. (2025) |
Burundi | |
Cameroon | |
| doi.org/10.1017/S0016756800064128 +8 other references |
Canada | |
| Dalsin (2013) +1 other reference |
| - (n.d.) |
| McClenaghan et al. (2009) |
| Liferovich et al. (2006) |
| Hogarth (1957) |
| Halpin et al. (2010) | |
| PDAC 2023 |
China | |
| Huang et al. (2026) |
| Wei et al. (2024) |
| Gu et al. (2007) |
| Xia et al. (2007) +1 other reference |
| Ruidong Yang et al. (2007) | |
| Li et al. (2025) | |
| Ou et al. (2026) |
| Fu et al. (2025) |
| Fengyi Chen et al. (1984) +4 other references |
| Weiguang Zhu et al. (2001) | |
| Cai et al. (2026) |
| Xiangrong Yang et al. (2009) |
Czech Republic | |
| Tasáryová et al. (2014) |
| Morávek P. |
| Morávek P. | |
| Ondruš et al. (2003) |
| Pauliš et al. (2017) |
| Fojt |
| Kudělásek |
| Kuttna +1 other reference |
| Pauliš | |
| Novotný et al. (2002) +2 other references |
| Prachař +6 other references |
| Houzar |
| Houzar S.: Zinkem a baryem bohaté minerální asociace (sfalerit - Zn-spinel - hyalofán - Ba-flogopit) |
| Novák et al. (2007) |
| Houzar +5 other references |
Eswatini | |
| Roerdink et al. (2016) |
Finland | |
| Sergeeva et al. (2011, February) |
France | |
| Vanaecker et al. (2014) |
| European J. Mineralogy |
Germany | |
| Walenta (1992) |
| Walenta (1992) |
| Riley et al. (2003) |
Greece | |
| Tsirigoti et al. (2025) |
Greenland | |
| Jakobsen (1990) +1 other reference |
Guatemala | |
| Ostrooumov et al. (2010) |
India | |
| Narasayya et al. (1974) |
| Raith et al. (2014) |
| Middlemost et al. (1988) +1 other reference |
| Kent et al. (1998) |
Ireland | |
| de Haller |
| Andrew et al. (2025) |
Italy | |
| Paolo Castello: Lo Ialofane e gli altri minerali del giacimento piombo-baritico del Trou des Romains (Courmayeur, Valle d'Aosta) +1 other reference |
| Frank K. Mazdab collection (see https://www.rockptx.com/fkm-151-to-fkm-175/#FKM-171 for normalized analysis) |
| Russo et al. (2004) |
| ... | |
| Stoppani et al. (1982) +1 other reference |
| Antofilli et al. (1983) |
| Mattioli (1979) +1 other reference |
| De Michele (1974) |
| Liotti (1991) |
| Biagioni et al. (2021) |
Japan | |
| Watanabe (1959) +1 other reference |
| Matsubara et al. (2010) |
| Shi et al. (2012) +1 other reference |
| Akira Kato (undated manuscript) |
| Am Min 90:1468 +1 other reference |
Kyrgyzstan | |
| Pekov (1998) |
Middle East | |
| Gross (1977) | |
Mongolia | |
| Savina et al. (2020) |
| Peretyazhko et al. (2017) |
| Peretyazhko et al. (2017) +1 other reference |
| Peretyazhko et al. (2017) | |
Myanmar | |
| Shi et al. (2012) |
| Shi et al. (2012) | |
Namibia | |
| Gauert (2005) |
| Viswanathan et al. (1980) +2 other references |
New Zealand | |
| Henderson (1983) |
North Macedonia | |
| Jančev et al. (2017) +1 other reference |
| Chukanov et al. (2015) | |
Norway | |
| Nordrum (2003) |
| Nordrum (2003) | |
| Nordrum et al. (2003) |
Peru | |
| Lewis (1964) |
Poland | |
| Pieczka A. et al. (2004) |
| SZUSZKIEWICZ et al. (2013) |
| Lis et al. (1986) |
| Vanaecker et al. (2014) |
Romania | |
| Hârtopanu et al. (1996) |
| Hârtopanu et al. (1996) +1 other reference |
| minerals-of-the-carpathians.eu (2008) |
Russia | |
| Sorokina et al. (2019) |
| Савельева et al. (2021) |
| Konstantin Klopotov's Data |
| И.И. et al. (2023) |
| Kovalev et al. (2023) |
| Safonov et al. (2003) |
| Kostin (2021) |
| Okrugin et al. (2023) |
| Okrugin et al. (2021) | |
| Stepanov et al. (2021) |
Slovakia | |
| Hurai et al. (2011) |
South Africa | |
| Rudnick et al. (2013) +1 other reference |
South Korea | |
| Gi Young Jeong (2006) |
| Cheong et al. (2003) |
| Gi Young Jeong (2006) |
Spain | |
| Moro et al. (2001) |
Sweden | |
| Geijer (1939) |
| |
| Augsten (2010) | |
| |
| Gatedal (n.d.) |
| Econ Geol (1992) | |
| Holtstam et al. (1999) +1 other reference |
| Gatedal (n.d.) +2 other references |
| Nysten (1984) +1 other reference |
Switzerland | |
| Weibel et al. (1990) |
| - (1983) +2 other references |
| www.mineralienatlas.de (n.d.) | |
| |
| Stalder et al. (1998) |
| 50. (in German) +1 other reference | |
| Stalder et al. (1998) +1 other reference |
| Stalder et al. (1998) |
UK | |
| Moles (2025) |
| Coats (1980) +3 other references | |
| Moles (2025) | |
| |
Ukraine | |
| Bondarenko +2 other references |
USA | |
| Steeves et al. (2016) |
| Slack et al. (2014) |
| Slack et al. (2014) | |
| Slack et al. (2014) | |
| Housley et al. (1999) |
| Dunning et al. (2003) |
| Carnein et al. (2005) |
| Schooner (circa 1980s) |
| McSwiggen et al. (1994) |
| Sandfire Resources America Inc. |
| Mitchell (2000) +1 other reference | |
| U.S. GEOLOGICAL SURVEY Open-File Report ... |
| Palache (1935) +3 other references |
| FOMS Millsite Committee (1986) | |
| MEIER (A. E.) |
| Sloto (2024) |
| Phillips et al. (2008, December) |
Western Sahara | |
| Meteoritical Society Abstracts (2001) |
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