| Falsterite | |
| Category: | Phosphate mineral |
| Formula: | Ca2MgMn2+2(Fe2+0.5Fe3+0.5)4 Zn4(PO4)8(OH)4(H2O)14 |
| Imasymbol: | Fls[1] |
| System: | Monoclinic |
| Class: | Prismatic (2/m) (same H-M symbol) |
| Symmetry: | P21/c |
| Unit Cell: | a = 6.39, b = 21.26 c = 15.37 [Å]; β = 90.56° (approximated); Z = 2 |
| Color: | Greenish-blue |
| Habit: | thin plates, rectangular laths |
| Cleavage: | , perfect |
| Fracture: | Uneven |
| Luster: | Vitreous |
| Streak: | Very pale greenish-blue |
| Diaphaneity: | Transparent |
| Density: | 2.78 (measured); 2.84 (calculated; approximated) |
| Opticalprop: | Biaxal (-) |
| Refractive: | nα=1.58, nβ=1.60, nγ=1.61 (approximated) |
| Pleochroism: | Colorless to very pale yellow (X & Z), blue-green (Y) |
| Dispersion: | Strong |
Falsterite is a rare phosphate mineral[2] with the formula Ca2MgMn2+2(Fe2+0.5Fe3+0.5)4Zn4(PO4)8(OH)4(H2O)14.[3] It is a pegmatitic mineral, related to the currently approved mineral ferraioloite.
Falsterite was found in Palermo No. 1 pegmatite, North Groton, Grafton County, New Hampshire, US. Co-type locality is pegmatite at Estes quarry, Baldwin, Cumberland County, Maine, US. Falsterite is a product of alteration of triphylite and sphalerite.
Main features of the crystal structure of falsterite, which is somewhat similar to that of schoonerite, are:
The slabs are bridged by dimers of MgO6 octahedra that display edge-sharing. Magnesium-bearing octahedra share edges with zinc-bearing tetrahedra.