2 adjectives to describe anthracite

The tutor breakfasts on coffee made of beans, edulcerated with milk watered to the verge of transparency; his mutton is tough and elastic, up to the moment when it becomes tired out and tasteless; his coal is a sullen, sulphurous anthracite, which rusts into ashes, rather than burns, in the shallow grate; his flimsy broadcloth is too thin for winter and too thick for summer.

The tutor breakfasts on coffee made of beans, edulcerated with milk watered to the verge of transparency; his mutton is tough and elastic, up to the moment when it becomes tired out and tasteless; his coal is a sullen, sulphurous anthracite, which rusts into ashes, rather than burns, in the shallow grate; his flimsy broadcloth is too thin for winter and too thick for summer.

2 adjectives to describe  anthracite