Formula: Cu3AsS4
Reflected/transmitted colour: opaque, polished section somewhat lighter than enargite, luzonite is pinkish orange, substitution by Sb makes it more pinkish without the orange tints
Pleochroism:
Optical isotropy/anisotropy: polished section very strong anisotropic, dark brown, grayish green, accentuated by compound twinning. Commonly oblique extinction with regard to the twin lamellae, Sb substitution results in more vivid polarisation colours
Optical sign:
Refractive indices:
Birefringence δ/bireflectance: polished section distinct to strong (in oil), lamellar twinning which is always present causes beautiful colour effects, orange-brown to grayish violet
2V angle:
Dispersion:
Optical orientation:
Optical axial plane:
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