Bredigite

Formula:  Ca₇Mg(SiO₄)₄

Origin of name:  For Max Albrecht Bredig (1902- ), physical chemist who studied the polymorphism of Ca₂SiO₄

Crystal system:  Orthorhombic pseudo-hexagonal

Crystal class:  2/m 2/m 2/m

Twinning: Simple contact and cyclic on {110}

Unit cell: a = 10.909 Å, b = 18.34 Å, c = 6.739 Å

Colour:  Colourless to gray

Diaphaneity: Transparent

Luster:  Vitreous

Habit:  rounded grains

Hardness: 

Specific gravity:  3.40

Cleavage:  1; {130} distinct

Tenacity:

Streak: White

Synonyms/varieties:

Comments: Found in contact metamorphosed limestones and dolostones intruded by diabase or syenite monzonite.