It's about time to try again
.
But this time be sure the metals are has Mu_r = 1 as in metals on chip such as gold,copper,alumnium (They have Mu_r very close to 1).
Probably in your childhood you used Iron which have Mu_r = 4000 or some
other metal with Mu_r > 1 these metals can store energy induced by magnetic
fields.
There is pretty much equivalence in this matter to E_r.
E_r - is storage of energy in molecules which organized in dipole due to electric field
Mu_r - is storage of energy by tiny magnetic dipoles in material induced by magnetic field.
Magnets for instance has permanent magnetic dipoles, unlike Iron
which magnetic dipoles induced by external field vanish as a times goes
due to thermal activity.
By the way, frequency shift could be also changed by inserting the metals even with
Mu_r=1.
Significant freq change can be due to floating metals,when they significally change the effective dielectric therefore the capacitance is changed which force frequency
to shift - but again the shift is due capacity not inductance change.
This why I stated before that Q changes and not the L.
Regads ,
Gosha