Mineral Information and Data:

Datolite
CaBSiO4(OH) [CNMNC approved formula]

Named From the Greek, dateisthai, meaning "to divide," because granular aggregates crumble readily.

IMA status : Valid species (Pre-IMA 1806) Grandfathered
CLASSIFICATION 
Dana
(8th edition) :
54.02.01a.01  
  (54) Nesosilicate Borosilicates and Some Beryllosilicates
  (54.02) with B in [4] coordination
  (54.02.01a) Datolite group (Datolite series)
  
Nickel-Strunz
(10th edition) :
09.AJ.20
  (09) Silicates
  (09.A) Nesosilicates (Isolated tetrahedron) structures
  (09.AJ) Nesosilicates with BO3 triangles and/or B[4], Be[4] tetrahedra, cornersharing with SiO4
  
Crystal system: Monoclinic System
Point group (H-M): 2/m — prismatic
Space group: P21/c
Unit cell: a =4.832(4)Å, b = 7.608(4)Å, c = 9.636(8)Å, β = 90:40(7)°, Z=4
Crystal Habit: Crystals typically short prismatic, with prominent {110}, {011}, or tabular on {010}, to 12 cm. Botryoidal or globular, having columnar structure; granular to compact; cryptocrystalline.
  
Color: Colorless or white, commonly with a greenish tinge; may be grayish, yellow, green, red, pink; in thin section, colorless
Diaphaneity: Transparent to translucent, rarely opaque
Luster: Vitreous, rarely subresinous on fracture surface
Hardness (Mohs): 5 - 5.5
Measured Density: 2.96 - 3.00 g/cm3
Tenacity: Brittle
Fracture: Conchoidal to uneven
  
Geologic Setting: A secondary mineral in mafic igneous rocks; in geodes in tuffs; in skarns in limestones; in serpentinites and "hornblende" schists; from some ore veins.
Mineral Association: Calcite, prehnite, zeolites, danburite, axinite, garnet
  
Luminescent Properties: Commonly fluoresces blue under SW UV.
Other Properties: Gemstone Extremely Rare.

 

Datolite
Origin: Sentyabri'skiy mine, near Dal'negorsk, Rudnaja River Valley, Primorskiy Kray, Russia
Sample size: 2.5 x 3 x 1.5 cm
Photo: Dan Weinrich

 

Datolite
(zoom-in of above)

 

Datolite
Origin: Paterson, New Jersey, U.S.A.
Sample size: 8 x 7 x 5.5 cm
Photo: Dan Weinrich

 

Datolite
(zoom-in of above)

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