Skip to main content

Physical properties; orthorhombic symmetry elements

Short answer

Physical properties include colour, streak, lustre, hardness, cleavage, fracture, tenacity, and specific gravity. The orthorhombic normal class has 3 planes of symmetry, 3 diad axes, and 1 centre of symmetry.

Describe the physical properties of minerals. What are the elements of symmetry of the orthorhombic system?

Physical properties of minerals

  • Colour and streak (colour of powder).
  • Lustre: metallic or non-metallic (vitreous, pearly, silky, earthy).
  • Hardness: Mohs scale (1-10).
  • Cleavage and fracture.
  • Tenacity: brittle, malleable, elastic.
  • Specific gravity.
  • Transparency and crystal habit.
  • Special: magnetism, taste, effervescence in HCl.

Symmetry elements of the orthorhombic system

Axes: a≠b≠ca \ne b \ne c, all at 90°. The normal class has:

  • 3 planes of symmetry (each parallel to a pair of axes).
  • 3 diad axes (along the a, b and c axes).
  • 1 centre of symmetry.

Total: 7 elements.

✓ Answer checked by Claude Opus 5.5 (high effort)

Related questions

All Engineering Geology I chapter 3 questions →