Milarite

KCa₂(Be₂AlSi₁₂)O₃₀·H₂OIMA symbol: Milgrandfathered

Milarite is a silicate mineral with the formula KCa2(Be2AlSi12)O30·H2O, crystallizing in the hexagonal system. It has a Mohs hardness of 5.5-6, typically colorless or green in color, with a vitreous luster, a specific gravity of 2.55-2.59. Cleavage is none.

Photos

Crystallography

Crystal system	hexagonal crystal systemWikidata (CC0)
Space group	P 6/m c c
Cell (Å, °)	a = 10.41, b = 10.41, c = 13.845; α = 90, β = 90, γ = 120
Cell volume	1299.35 Å³, Z = 2
Axial ratios	1.0000:1:1.3300calculated from COD 9001381
Source structure	COD 9001381 (American Mineralogist, 1991) — 1 of 11 structures

Powder X-ray diffraction (calculated)

d (Å)	3.309	2.882	4.16	5.205	6.923	2.745
I/I₀	100	72.6	49.4	43.3	31.3	28.8

xrd-v1: CuKa1 1.5406A, 2theta 5-90, top10, Imax=100, no DW/PO. Computed from COD 9001381; idealized occupancies, no preferred orientation.

Physical properties

Density (calculated)	2.538 g/cm³calculated from COD 9001381
Hardness (Mohs)	5.5-6single sourceDana, System of Mineralogy, 6th ed. (1892)
Specific gravity	2.55-2.59 g/cm3corroboratedDana, System of Mineralogy, 6th ed. (1892)
Color	colorless, greensingle sourceDana, System of Mineralogy, 6th ed. (1892)
Luster	vitreoussingle sourceDana, System of Mineralogy, 6th ed. (1892)
Cleavage	noneDana, System of Mineralogy, 6th ed. (1892)

Chemistry (calculated)

Molecular weight	999.28 g/molcalculated from the IMA formula
Composition (wt%)	K 3.91%, Ca 8.02%, Be 1.8%, Al 2.7%, Si 33.73%, O 49.63%, H 0.2%

Classification

Nickel-Strunz (10th)	9.CM.05Wikidata (CC0)
Nickel-Strunz (9th)	9.CM.05Wikidata (CC0)