They're

  only

Adverbio

  made of

  rock crystal

,  and

Conxunción coordinadora

  there are

  millions

Substantivo

  of

Adposición

  rock crystals

  in

Adposición

  the

Determinador

  earth

Substantivo

.

They're only made of rock crystal, and there are millions of rock crystals in the earth.

They're only made of rock crystal, and there are millions of rock crystals in the earth.