Brittle

having hardness and rigidity but little tensile strength; breaking readily with a comparatively smooth fracture, as glass.
easily damaged or destroyed; fragile; frail:
a brittle marriage.
lacking warmth, sensitivity, or compassion; aloof; self-centered:
a self-possessed, cool, and rather brittle person.
having a sharp, tense quality:
a brittle tone of voice.
unstable or impermanent; evanescent.
a confection of melted sugar, usually with nuts, brittle when cooled:
peanut brittle.
to be or become brittle; crumble.
Contemporary Examples

Pumpkin Seed Brittle The Daily Beast November 24, 2008
You’re Never ‘Cured’ of an Eating Disorder Carrie Arnold December 19, 2014
Eulogy for Don Draper’s Secretary The Daily Beast Video September 19, 2010
America’s Bacon Addiction Sarah Whitman-Salkin June 29, 2009
Newt Gingrich’s Wife Callista’s Prissy Style Problem Robin Givhan December 12, 2011

Historical Examples

The Biography of a Prairie Girl Eleanor Gates
The Inn at the Red Oak Latta Griswold
Christmas Outside of Eden Coningsby Dawson
The Mushroom, Edible and Otherwise M. E. Hard
Scurvy Past and Present Alfred Fabian Hess

adjective
easily cracked, snapped, or broken; fragile
curt or irritable: a brittle reply
hard or sharp in quality
noun
a crunchy sweet made with treacle and nuts: peanut brittle
adj.
brittle
(brĭt’l)
Having a tendency to break when subject to high stress. Brittle materials have undergone very little strain when they reach their elastic limit, and tend to break at that limit. Compare ductile.