How meteors became dense?

With my layman's understanding of meteors, they are very dense objects
(as compared to loosely compacted comets). At least dense enough to
survive falling through Earth's atmosphere to hit the ground. If they
formed from a dust cloud as the rest of the solar system did, how did
they compact so densely? They aren't large enough for gravity to
compact them. Thanks.

John wrote:
With my layman's understanding of meteors, they are very dense objects
(as compared to loosely compacted comets). At least dense enough to
survive falling through Earth's atmosphere to hit the ground. If they
formed from a dust cloud as the rest of the solar system did, how did
they compact so densely? They aren't large enough for gravity to
compact them. Thanks.

I think they are from planetessimals that got big enough and hot
enough to melt metals and rocky materials (and, perhaps separate those
materials) at one point in their formation, that were subsequently
blasted into small fragments by large collisions.

John,

All small meteoroids orbiting the Sun now are fragments
of larger objects. Still, none of those larger objects
was ever as large as Earth, and the largest must be Mars,
from which several meteorites have been found.

The smallest meteoroids are slowed in their orbits by the
Poynting-Robertson effect, which causes them to slowly
spiral closer to the Sun. If they don't run into a planet
first, they are vaporized by the Sun's heat and the vapor
is blown away by solar wind. So small objects are
constantly removed from the Solar System.

Iron and many stony meteoroids were once part of asteroids
large enough to melt and separate by density. Heavy iron
and nickle sank to the center of the asteroid and lighter
rock stayed at the surface. When asteroids collided, a
variety of different meteoroid compositions emerged from
the rubble.

Chondritic meteoroids are interesting in that they have
never been part of asteroids which melted. Yet they can
be quite compact. I have handled chondritic meteorites
which have been sawn open, and they are very solid rock.
But the separate grains, or chondrules, are obvious.
They have been pressed together very tightly by gravity
in asteroids one or two hundred kilometers in diameter.

There are still some less dense, less-compacted bodies in
orbit around the Sun, including carbonaceous chondrites.
They usually disintigrate completely when they enter
Earth's atmosphere, leaving behind no identifiable
meteorites.

-- Jeff, in Minneapolis