Mineral Information and Data:

Ca4Mg2Al4[B2Si8O30](OH)2 [CNMNC approved formula]

Named in 1975 for the dominant mangnesium in a mineral of the axinite group, named from the Greek for axe after their sharp crystal forms.

IMA status : Renamed IMA Approved; 2008 (IMA1975-025)
(8th edition) :  
  (56) Sorosilicate Si2O7 Groups and O, OH, F. and H2O
  (56.02) with cations in [4] and/or >[4] coordination
  (56.02.02) Axinite group
(10th edition) :
  (09) Silicates
  (09.B) Sorosilicates (dimer) structures
  (09.BD) Si2O7 groups, with additional anions; cations in tetrahedral [4] and greater coordination
Crystal system: Triclinic System
Point group (H-M): 1 — pedial
Unit cell: a = 8.93Å, b = 9.15Å, c = 7.12Å; α = 102.59°, β = 98.28°, γ = 88.09°
Crystal Habit: As crystals, to 3 cm, with the axe-head-shaped morphology typical of axinites; originally found as a rough gemstone.
Color: Pale blue to pale violet; light brown to light pink
Diaphaneity: Transparent to translucent
Luster: Vitreous
Hardness (Mohs): 6.5 - 7
Measured Density: 3.178 g/cm3
Cleavage: Good on {100}, poor on {001}, {110}, and {011}
Tenacity: Brittle
Fracture: Uneven to conchoidal
Streak: White
Geologic Setting: Typically a mineral formed during contact metamorphism and boron
Mineral Association: Epidote, tremolite, calcite (London Bridge, Australia); prehnite, epidote, actinolite, vesuvianite (Luning, Nevada, USA).
Synonyms/varieties: Magnesio-axinite, Magnesium Axinite
Luminescent Properties: Fluoresces red-orange in LW UV, duller red in SW UV.
Other Properties: Gemstone Readily Available.