Ruitenbergite

Formula: Ca₉B₂₆O₃₄(OH)₂₄C₄.13H₂O

Origin of name: for Arie Ruitenberg, Canadian geologist

Crystal system: monoclinic

Crystal class: 2

Twinning:

Unit cell: 

Colour: colourless to pale yellow

Diaphaneity: 

Luster: vitreous

Habit: platy to prismatic subhedral to anhedral grains to 2 mm, aggregates to 4 mm

Hardness: 3 to 4

Specific gravity: 2.21

Cleavage: 1; {100} good

Tenacity: 

Streak: white

Synonyms/varieties:

Comments: dimorphous with pringleite, only a single grain known