Bandylite
CuB(OH)4Cl [CNMNC approved formula]
Named for Mark Chance Bandy (1900-1963), American mining engineer, mineralogist, and mineral collector, who first collected the mineral.
| IMA status : | Valid species (Pre-IMA 1938) Grandfathered |
| CLASSIFICATION | |
| Dana (8th edition) : |
25.01.04.02 |
| (25) Anhydrous Borates Containing Hydroxyl or Halogen | |
| (25.01) | |
| (25.01.04) | |
| Nickel-Strunz (10th edition) : |
06.AC.35 |
| (06) Borates | |
| (06.A) Monoborates | |
| (06.AC) B(O,OH)4, without and with additional anions; 1(T), 1(T)+OH, etc | |
| Crystal system: | Tetragonal System |
| Point group (H-M): | 4/mmm (or 4/m 2/m 2/m) — ditetragonal-dipyramidal |
| Unit cell: | a = 6.19Å, c = 5.61Å |
| Crystal Habit: | As crystals, typically tabular on {001} or pyramidal, to 5 mm; dominant forms are {001}, {111}, {201}, and {110}; also as radial clusters, almost lichen-like, in joints in the rock. |
| Color: | Deep blue with greenish portions; cendre blue to Italian blue, becoming greener with atacamite inclusions; blue in transmitted light. |
| Diaphaneity: | Transparent |
| Luster: | Vitreous, pearly on cleavage surfaces; dull when altered. |
| Hardness (Mohs): | 2.5 |
| Measured Density: | 2.810 g/cm3 |
| Cleavage: | {001}, perfect |
| Tenacity: | Very flexible; easily deformed. |
| Streak: | Pale blue |
| Geologic Setting: | Of secondary origin, in a leached zone above massive iron sulfates (Quetena, Chile). |
| Mineral Association: | Atacamite, eriochalcite (Quetena, Chile); starkeyite (near Taltal, Chile) |
| Other Properties: | H2O Soluble. |
| Comments: | Alters to eriochalcite on exposure to air. |