A curved horn (this horn was a musical instrument composed of segments of animal horns)

is tamei (as utensils made of bone are tamei if they have a receptacle, which in this case is present due to the curve)

and a straight one is tahor.

If its mouthpiece

was of metal

it (the entire horn) is tamei.

Its bell (the wide end of the horn),

Rabbi Tarfon rules is tamei (if made of metal, even while detached)

and the Sages rule is tahor (as its name must be qualified; just calling it a "bell" is not enough to know what is being referred to);

and when they are attached (when all parts of the horn are attached to each other, including this metal bell)

everything is tamei.

Similarly,

the branches of a candelabra are tahor (when detached).

The flower (this was a flower-shaped part of candelabra that held the lamp)

and the base

are tamei (even when detached, as they function as receptacles),

and when attached

everything is tamei.

פרק יא משנה ח

A helmet (which was made of bronze) is tamei

and its cheek-guards are tahor,

if they have

a receptacle for water

they are tamei.

All implements of war

are tamei.

A light spear (held by leaders as a symbol of authority),

and a spearhead,

and greaves (armor used to protect the shins),

and a coat of mail,

are tamei.

All women's jewelry

are tamei:

a city of gold (a gold headpiece shaped like Jerusalem)

chokers,

earrings,

and rings;

a ring

whether it has a signet

whether it does not have a signet;

and nose rings.

A choker

whose beads are of metal

on a string of flax

or of wool,

if the string breaks,

the beads are tamei

as each one

is a utensil by itself (one can put a single bead on a string).

[If] the string was of metal

and the beads were of precious stones

and of pearls

and of glass,

the beads broke

and the string remained by itself,

it is tamei (as it can be used as a necklace by itself).

The remnant of a choker (that had broken)

(is long enough to encircle) the width of the neck of a girl ,

Rabbi Eliezer says

even a single ring (meaning even if only one bead remains),

it is tamei,

as such (a small ornament) is hung on the neck.