eschar

noun3

1. •
   A superficial structure of dead tissue, usually hardened, and commonly but not necessarily dark, adhering to underlying living or necrotic tissue, caused by gangrene or a burn.
2. •
   Any hard, dark, commonly flattened or sunken lesion or crust, especially on a burn, abscess, infection, wound; commonly a coagulation of blood or exudations, not necessarily involving dead or necrotic tissue.

   • When the caustic is removed, the eschar should be punctured for the discharge of the matter, and then dressed with warm emollient poultices... — 1779
3. •
   (literary, figurative) The emotional imprint of a trauma such as grief, loss, or degradation.

   • In another minute there was no letter; but, as with every other relationship in my life, an eschar of ashes. The word is rare, but exact. — 1965