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Heulandite-Ca

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Formula:
(Ca,Na,K)5(Si27Al9)O72 · 26H2O
System:
Monoclinic
Colour:
White, Colorless, Red, ...
Lustre:
Vitreous, Pearly
Hardness:
3½ - 4
Name:
Named in 1822 by Henry James Brooke in honor of Johann Heinrich "John Henry" Heuland [March 21, 1778 Beyreuth, Germany - November 16, 1856 Hastings, Sussex, England, UK], a mineral collector and mineral dealer living in England and for the suffix indicating dominant Ca. Despite having an international reputaion, there are no known images of Henry Heuland.

Classification of Heulandite-Ca

Approved, 'Grandfathered' (first described prior to 1959)
Approval Year:
1997
9.GE.05

9 : SILICATES (Germanates)
G : Tektosilicates with zeolitic H2O; zeolite family
E : Chains of T10O20 Tetrahedra
Dana 7th ed.:
77.1.4.1
77.1.4.1

77 : TECTOSILICATES Zeolites
1 : Zeolite group - True zeolites

Physical Properties of Heulandite-Ca

Vitreous, Pearly
Diaphaneity (Transparency):
Transparent
Comment:
Pearly on cleavage {010}
Colour:
White, Colorless, Red, Yellow, Brown, Green
Streak:
White
Hardness (Mohs):
3½ - 4
Tenacity:
Brittle
Cleavage:
Perfect
Perfect on the {010}
Fracture:
Irregular/Uneven, Sub-Conchoidal
Density:
2.1 - 2.2 g/cm3 (Measured)    2.17 g/cm3 (Calculated)

Optical Data of Heulandite-Ca

Type:
Biaxial (+)
RI values:
nα = 1.491 - 1.505 nβ = 1.493 - 1.503 nγ = 1.500 - 1.512
2V:
Measured: 10° to 48°
Max Birefringence:
δ = 0.009
Image shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:
Moderate
Dispersion:
r > v distinct

Chemical Properties of Heulandite-Ca

IMA Formula:
(Ca,Na,K)5(Si27Al9)O72 · 26H2O
Elements listed in formula:

Crystallography of Heulandite-Ca

Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
B2/m
Space Group Setting:
C2/m
Cell Parameters:
a = 17.73Å, b = 17.82Å, c = 7.43Å
β = 116.33°
Ratio:
a:b:c = 0.995 : 1 : 0.417
Unit Cell Volume:
V 2,103.96 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Coffin-shaped tabular crystals, granular, massive.
Twinning:
{100} is twin and contact plane
Comment:
Merkle & Slaughter (1967). The reduced cell has beta ~113°. May be triclinic due to Al-Si ordering.

Occurrences of Heulandite-Ca

Type Occurrence of Heulandite-Ca

Relationship of Heulandite-Ca to other Species

Series:
Forms a series with Clinoptilolite-Ca (see here)
Other Members of Group:
Heulandite-Ba(Ba,Ca,K)5(Si27Al9)O72 · 22H2O
Heulandite-K(K,Ca,Na)5(Si27Al9)O72 · 26H2O
Heulandite-Na(Na,Ca,K)6(Si,Al)36O72 · 22H2O
Heulandite-Sr(Sr,Na,Ca)5(Si27Al9)O72 · 24H2O
Common Associates:
9.GE.05Clinoptilolite-CaCa3(Si30Al6)O72 · 20H2O
9.GE.05Clinoptilolite-KK6(Si30Al6)O72 · 20H2O
9.GE.05Clinoptilolite-NaNa6(Si30Al6)O72 · 20H2O
9.GE.05Heulandite-K(K,Ca,Na)5(Si27Al9)O72 · 26H2O
9.GE.05Heulandite-Na(Na,Ca,K)6(Si,Al)36O72 · 22H2O
9.GE.05Heulandite-Sr(Sr,Ca,Na)5(Si27Al9)O72 · 24H2O
9.GE.05Heulandite-Ba(Ba,Ca,K)5(Si27Al9)O72 · 22H2O
9.GE.10Stilbite-CaNaCa4(Si27Al9)O72 · 28H2O
9.GE.10Stilbite-NaNa9(Si27Al9)O72 · 28H2O
9.GE.15BarreriteNa2(Al2Si7)O18 · 6H2O
9.GE.15StelleriteCa4(Si28Al8)O72 · 28H2O
9.GE.20Brewsterite-BaBa(Al2Si6)O16 · 5H2O
9.GE.20Brewsterite-SrSr(Al2Si6)O16 · 5H2O
77.1.4.1Heulandite-K(K,Ca,Na)5(Si27Al9)O72 · 26H2O
77.1.4.1Heulandite-Na(Na,Ca,K)6(Si,Al)36O72 · 22H2O
77.1.4.1Heulandite-Sr(Sr,Ca,Na)5(Si27Al9)O72 · 24H2O
77.1.4.3Stilbite-CaNaCa4(Si27Al9)O72 · 28H2O
77.1.4.3Stilbite-NaNa9(Si27Al9)O72 · 28H2O
77.1.4.5BarreriteNa2(Al2Si7)O18 · 6H2O

Other Names for Heulandite-Ca

Name in Other Languages:

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.

References for Heulandite-Ca

Reference List:
Merkle, A.B., and M. Slaughter (1968), Determination and refinement of the structure of heulandite: American Mineralogist: 53: 1120-1138.

Alberti, A. (1972), On the crystal structure of the zeolite heulandite: Tschermaks Mineralogische und Petrographische Mitteilungen: 18: 129-146.

Fahri Esenli and Isik Kumbasar (1998) X-Ray Diffraction Intensity Ratios I(111)//(311) of Natural Heulandites and Clinoptilolites, Clays and Clay Minerals, Vol. 46, No. 6, 679-686, 1998.

Comodi, P., G.D. Gatta, & P.F. Zanazzi (2001), High-pressure structural behavior of heulandite: European Journal of Mineralogy: 15: 247-255.

Internet Links for Heulandite-Ca

mindat.org URL:
http://www.mindat.org/min-6988.html
Please feel free to link to this page.
Specimens:
The following Heulandite-Ca specimens are currently listed for sale on minfind.com.

Localities for Heulandite-Ca

map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
Mineral and/or Locality  
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