Leonhardite
A variety of Laumontite
This page is currently not sponsored. Click here to sponsor this page.
About Leonhardite
Karl von Leonhard
Formula:
CaAl2Si4O12 · 3H2O
Name:
Named by Johann Reinhard Blum in 1843 in honor of Karl Caesar von Leonhard [September 12, 1779, Rumpenheim bei Hanau, Germany - January 23, 1862, Heidelberg, Germany]. Von Leonard was variously a tax assessor and administrator of the Grand Duchy of Frankfurt. Eventually, he became Professor of mineralogy at the University of Heidelberg. One of von Leonhard's discourses involved the first concept of loess, its occurrence, and properties.
A name for partially dehydrated, opaque laumontite.
Leonhardite seems to be stabilised by the presence of Na and K.
Notes:
Stolz & Armbruster (1997) refined, in space group C2/m, the crystal structure of a (Na,K)-rich laumontite with the simplified formula Na1.85K1.85Ca2.15 [Al8Si16O48].13.53H2O. "Na replaces Ca whereas K resides on a site occupied by H2O in ordinary laumontite. Incorporation of K has two effects: (1) it reduces the amount of H2O in the structural channels; (2) it prevents re- and dehydration under room temperature conditions because symmetry related K sites are only 4.8 Å apart, thus reducing the free aperture of the channels. The chemically unusual laumontite studied in this paper exhibits a tetrahedral framework with well ordered Si, Al distribution as known for ordinary laumontite".
Baur et al. (1997) distinguish a primary and a secondary leonhardite; their abstract reads: "Primary leonhardite, Ca2.55K1.59Na1.24FeO.O3Al8.19Si15.87O48 • l3.93H2O, with a primitive Bravais lattice, is a leonhardite that cannot be hydrated and is not formed by the dehydration of laumontite. It crystallizes in space group P12/a1 with a = 14.556(4) Å, b = 13.206(3) Å, c = 7.513(3) Å, ß = 110.75(2)°, V = 1351(1) Å3 and Z = l. Even though P12/a1 is a subgroup of C12/m1 (the space group of laumontite and secondary leonhardite), the geometry of the aluminosilicate framework and the distribution of Al and Si atoms in primary leonhardite are extremely close to what is known for laumontite (Ca4Al8Si16O48 • 18H2O) and partly dehydrated laumontite (Ca4Al8Si16O48 • 14H2O). Because Na and K substitute for Ca in the pores of primary leonhardite in an ordered way, its symmetry is reduced compared with laumontite. Because the total number of pore-filling cations is larger than in any other known laumontite (due to the replacement of Ca by univalent cations) primary leonhardite cannot accomodate as many water molecules in its pores as laumontites."
Leonhardite seems to be stabilised by the presence of Na and K.
Notes:
Stolz & Armbruster (1997) refined, in space group C2/m, the crystal structure of a (Na,K)-rich laumontite with the simplified formula Na1.85K1.85Ca2.15 [Al8Si16O48].13.53H2O. "Na replaces Ca whereas K resides on a site occupied by H2O in ordinary laumontite. Incorporation of K has two effects: (1) it reduces the amount of H2O in the structural channels; (2) it prevents re- and dehydration under room temperature conditions because symmetry related K sites are only 4.8 Å apart, thus reducing the free aperture of the channels. The chemically unusual laumontite studied in this paper exhibits a tetrahedral framework with well ordered Si, Al distribution as known for ordinary laumontite".
Baur et al. (1997) distinguish a primary and a secondary leonhardite; their abstract reads: "Primary leonhardite, Ca2.55K1.59Na1.24FeO.O3Al8.19Si15.87O48 • l3.93H2O, with a primitive Bravais lattice, is a leonhardite that cannot be hydrated and is not formed by the dehydration of laumontite. It crystallizes in space group P12/a1 with a = 14.556(4) Å, b = 13.206(3) Å, c = 7.513(3) Å, ß = 110.75(2)°, V = 1351(1) Å3 and Z = l. Even though P12/a1 is a subgroup of C12/m1 (the space group of laumontite and secondary leonhardite), the geometry of the aluminosilicate framework and the distribution of Al and Si atoms in primary leonhardite are extremely close to what is known for laumontite (Ca4Al8Si16O48 • 18H2O) and partly dehydrated laumontite (Ca4Al8Si16O48 • 14H2O). Because Na and K substitute for Ca in the pores of primary leonhardite in an ordered way, its symmetry is reduced compared with laumontite. Because the total number of pore-filling cations is larger than in any other known laumontite (due to the replacement of Ca by univalent cations) primary leonhardite cannot accomodate as many water molecules in its pores as laumontites."
Unique Identifiers
Mindat ID:
26821 (as Leonhardite)
2340 (as Laumontite)
2340 (as Laumontite)
Long-form identifier:
mindat:1:1:26821:1 (as Leonhardite)
mindat:1:1:2340:1 (as Laumontite)
mindat:1:1:2340:1 (as Laumontite)
Similar Names
| Leonhardtite | A synonym of Starkeyite |
IMA Classification of Leonhardite
Discredited
Chemistry of Leonhardite
Mindat Formula:
CaAl2Si4O12 · 3H2O
Element Weights:
Other Language Names for Leonhardite
German:Leonhardit
Common Associates
Associations Based on Photo Data:
| 11 photos of Leonhardite associated with Calcite | CaCO3 |
| 6 photos of Leonhardite associated with Laumontite | CaAl2Si4O12 · 4H2O |
| 1 photo of Leonhardite associated with Pyrite | FeS2 |
| 1 photo of Leonhardite associated with Stilbite Subgroup | M6-7[Al8-9Si27-28O72] · nH2O |
| 1 photo of Leonhardite associated with 'Bakerite' | Ca4(H5B5Si3O20) |
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 Leonhardite
mindat.org URL:
https://www.mindat.org/min-26821.html
Please feel free to link to this page.
Please feel free to link to this page.
Search Engines:
Mineral Dealers:
References for Leonhardite
Reference List:
Blum, Dr. (1843) Leonhardit, ein neues Mineral. Annalen der Physik und Chemie, 135. 336-339 doi:10.1002/andp.18431350612
Coombs, D.S. (1952) Cell size, optical properties and chemical composition of laumontite and leonhardite. With a note on regional occurrences in New Zealand. American Mineralogist, 37 (9-10) 812-830
Kaley, M. E.; Hanson, R. F. (1955) Laumontite and leonhardite cement in Miocene sandstone from a well in San Joaquin valley, California. American Mineralogist, 40 (9-10). 923-925
Lapham, Davis M. (1963) Leonhardite and laumontite in diabase from Dillsburg, Pennsylvania. American Mineralogist, 48 (5-6) 683-688
Stolz, Jano, Armbruster, Thomas (1997) X-ray single-crystal structure refinement of Na, K-rich laumontite, originally designated 'primary leonhardite'. Neues Jahrbuch für Mineralogie - Monatshefte, 1997 (3) 131-144 doi:10.1127/njmm/1997/1997/131
Baur, Werner H., Joswig, Werner, Fursenko, Boris A., Belitsky, Igor A. (1997) Symmetry reduction of the aluminosilicate framework of LAU topology by ordering of exchangeable cations: the crystal structure of primary leonhardite with a primitive Bravais lattice. European Journal of Mineralogy, 9 (6) 1173-1182 doi:10.1127/ejm/9/6/1173
Localities for Leonhardite
Showing 7 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.
Australia | |
| Pinkstone (1962) |
Austria | |
| Kolitsch et al. (2026) |
China | |
| Shen (n.d.) |
India | |
| Ottens et al. (2022) |
Jordan | |
| Khoury et al. (1985) |
New Zealand | |
| Osborne Hutton (1944) |
USA | |
| Gilpin R. Robinson (1992) |
Grace Mine, Morgantown, Berks County, Pennsylvania, USA