Allargentum

Aguilarite

COLOR

White. Grey in contact with native silver. Takes a good polish in spite of its softness.

REFLECTANCE

High. Definitely lower than silver but higher than dyscrasite.

ANISOTROPISM

Weak and without shades. Tints are grey and become somewhat lighter by uncrossing the Nicole.

TEXTURE

The mineral occurs as lamellar exsolution in anatomy-rich silver. The inter growth is enclosed by pure silver. It has often been mistake for dyscrasite.

ASSOCIATED MINERALS

Native silver, nickeling, breithauptite, pararammelsbergite, rammelsbergite, silver-bismuth minerals.

CRITERIA OF DETERMINATION

Because of its high reflectance, allargentum can be confused only with dyscrasite which is practically never lamellar and polarizes a little more strongly. Native silver has a higher reflectance and is isotropic. Antimony and allemontite polarize much more strongly.

Source

ATLAS OF ORE MINERALS (P. Picot and Z. Johan)