Why is Piggy so concerned about the conch?Why do you think Golding describes it here as so "fragile and white"? Lord of the Flies by William Golding

In Chapter Eleven of The Lord of the Flies
after the fire has been stolen, comes the climax in the confrontation of
Piggy and Ralph as representatives of civilization against Jack and his tribe.  Having
had his glasses stolen, Piggy tells Ralph that he is going to Jack and the others with
the conch and ask for his glasses back.  Ralph knows, too, that he must confront Jack
and attempt to restore order.  He holds out the conch to Piggy, who takes it with
pride.

Jack, knowing, too, "that this was a crisis,"
charges Ralph, who deals him a blow.  They face off, "unnerved by each other's
ferocity."  Piggy yells that he has the conch, and against the booing of the boys, he
lifts the "white, magic shell."  Then, Ralph tries to reason with the boys by asking
them,

"Which
is better, law and rescue, or hunting and breaking things
up?"

But, Jack yells and
Ralph can no longer be heard. 

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By him stood Piggy still holding out the
talisman, the fragile, shining beauty of the
shell.

However, the talisman,
the conch, holds power over the boys no more as total anarchy has taken hold.  The
sadistic Roger, "with a sense of delirious abandonment," leans upon a level and sends a
pink granite rock upon Piggy, sending him to his death.  Jack bounds suddenly, screaming
wildly:  "There isn't a tribe for you any more!  The conch is
gone."

The conch, a symbol of civilization and order, has
been destroyed as Piggy, its blind worshipper and the voice of reason, is killed.  The
fragile order that Ralph and Piggy have established has been destroyed.  Symbolic of the
total anarchy, Roger advances upon the others "as one wielding a nameless
authority."