Goosecreekite |Ca2(H2O)10| [Al4Si12O32]
Rough crystals of goosecreekite, each about 3 cm long, from quarries on Malegaon hill, Nasek, India
  Tabular parallel to {010} to 8 cm; in groups of nearly parallel crystals
Physical properties:
  Cleavage: {101} perfect
Hardness: 4.5
Density:  2.21 g/cm3
Luster: vitreous to pearly
Streak:  white
Optical properties:            Goosecreekite
  Color: colorless to white; colorless in thin section.
Biaxial (- or +). α = 1.495, β = 1.498, γ = 1.502, δ = 0.007, 2Vx = 82°. Z ˄ c = 46°, Y = b. O.A.P || (010)
  Unit cell data:

a  7.401 Å
b  17.439 Å
c  7.293 Å
β 105.44°
Z = 1,  Space group P21
  Goosecreekite was described and named by Dunn et al. (1980) for the type locality at the Goose Creek quarry, Leesburg, Loudoun County, Virginia, U.S.A.
Crystal structure:  

The framework of goosecreekite (GOO) consists of almost completely ordered (Si,Al) tetrahedra (Rouse and Peacor 1986). In the accompanying figure green tetrahedra are AlO4 and the gray are SiO4.Goosecreekite The structure can be constructed from corner- and edge-sharing four-membered rings. Strongly deformed eight-membered rings (aperture 4.0 x 2.8Å) confine channels parallel to the a-axis, which are connected by additional eight-ring channels (aperture 2.7 x 4.1 Å) running zigzag-wise parallel to the b-axis. Eight-membered ring channels also run parallel to the c*-axis. Ca is located roughly at the intersection of these channels and bonds to two framework oxygens and five H2O molecules. All H2O molecules are bonded to Ca.

Chemical composition:
  There is only one published analysis for goosecreekite (Dunn et al. 1980). The ordered structure yields the TSi value of 0.75. Unpublished data show no cations other than Ca in samples from India.
  In general goosecreekite occurs in silica saturated environments at fairly high temperatures (for zeolites). One such environment is the hydrothermal alteration in the late stages of pegmatite crystallization or deuteric alteration of other intrusives. It has also been found in basalt cavities in western India, where the geothermal gradient at the time crystallization was high.
  Diagenesis of mafic lava flows
There are three known occurrences of goosecreekite in basalt cavities that may have originated from diagenetic alteration of basalt in a region of high heat flow (Wise and Moller 1990). Large crystals of goosecreekite have been found in three localities in state of Maharashtra in western India, occurring in cavities in the tholeiitic Deccan basalt. The largest are at Pandulena Quarry near Nasik, where it occurs on quartz and is associated with mordenite, heulandite, stilbite, and apophyllite (Tschernich 1992). It also occurs 80 km east of Pandulena, and at Kalyan northeast of Bombay.

Hydrothermal alteration
There are several occurrences of goosecreekite that resulted from deuteric alteration or reactions with late stage fluids. At the type locality Goose Creek quarry, London County, Virginia, goosecreekite formed in alteration seams in Triassic diabase. It is associated with albite, epidote, prehnite, babingtonite, stilbite. and actinolite.

Goosecreekite occurs in the late stage alteration zone in pegmatitic dikes cutting Paleozoic amphibolite at the Oberbaumühle Quarry near Windischeschenbach, Upper Palatinate, Bavaria, Germany. Sparse, tiny crystals have formed on epidote altered potassium feldspar and occurs with stilbite and laumontite (Hampel and Keck 1990).

Rare goosecreekite crystals occur in the late stage alteration zone of a granitic pegmatite at the Jensen quarry near Riverside, Riverside County, California, USA. Also in these late cavities are microcline, elbaite, muscovite, and stilbite (DeVito and Ordway 1984). .


DeVito, F. and Ordway, A., Jr. 1984. The Jensen Quarry, Riverside County, California. Min. Rec. 15, 273-290.

Dunn, P.J., Peacor, D.R., Newberry, N. and Ramik, R.A. 1980. Goosecreekite, a new calcium aluminum silicate hydrate possibly related to brewsterite and epistilbite. Can Mineral. 18, 323-327.

Hampel, W. and Keck, E. 1990. Goosecreekit von der Oberbaumühle bei Windischeschenbach (Oberpfalz). Lapis 14, 40-41.

Rouse, R.C., and Peacor, D.R. 1986. Crystal structure of the zeolite mineral goosecreekite, CaAl2Si6O16•5H2O. Am. Mineral. 71, 1494-1501.

Tschernich, R.W. (1992) Zeolites of the World, Geoscience Press, Phoenix, Arizona. 563 pp.

Wise, W.S. and Moller, W.P. (1990) Occurrence of Ca-Fe silicate minerals with zeolites in basalt cavities at Bombay, India. Eur. J. Mineral. 2, 875-883.