Re: can i make an electret from basalt (or granite) and barium titanate?

Electricity and magnetism are fascinating because they seem to be
mysterious forces, and so it is with materials that have a permanent
electric charge.

All materials can be classified as conductors, semi-conductors, and
insulators, or materials that conduct electricity very poorly.  Just
because a material doesn't conduct electric current well doesn't mean that
electric fields have no influence on them.

Many molecules are polar, in other words, the molecule has one end that has
a positive electrical charge, and the other end has a negative electrical
charge, water being a good example.  When a strong electric field is
applied to these polar molecules, they orient themselves with respect to
the external electric field, so the positive end of the molecule is facing
toward the negatively charged plate, and the negatively charged end of the
molecule is facing the positively charged plate.  If you freeze a material
while its molecules are aligned by the external electric field, then the
resulting material exhibits a permanent electric charge.  Even molecules
which are not polar can respond to external electrostatic fields and become
electrets due to surface charges.

According to Wikipedia "Electret materials are quite common in nature.
Quartz and other forms of silicon dioxide, for example, are naturally
occurring electrets. Today, most electrets are made from synthetic
polymers, e.g. fluoropolymers, polypropylene, polyethyleneterephthalate,
etc. Real-charge electrets contain either positive or negative excess
charges or both, while oriented-dipole electrets contain oriented dipoles."
http://en.wikipedia.org/wiki/Electret

Since a significant component of granite is quartz, one would expect that
the combinations you suggest may well be electrets if solidified and cooled
in a high voltage electric field.

The use of electrets as a source of electric charge has been used in a
device called the electrophorus.  (See http://www.ece.rochester.edu/~jones/demos/electrophorus.html.
 A metal
plate was placed on an electret made of wax.  The permanent electric charge
of the electret caused positive charges to collect on the bottom of the
metal plate, and negative charges to collect on the top.  By touching the
top surface of the plate with a finger, some of the negative charge would
be conducted away from the plate, leaving the metal plate with a net
positive charge.

T. Townsend Brown was a strong advocate for the electret, believing that
the electrostatic forces generated by the electret were somehow related to
gravity (potentially offering an antigravity effect).  This may have been
the basis for the anti-gravity paint in Danny Dunn and the Anti-Gravity
Paint by Jay William.  Alas, electrostatic forces are no more anti-gravity
forces than are magnetic forces.

More recently some have thought that the permanent electrical charge
contained within the electret could be a source of "free" electric energy.
And the electrophorus indeed demonstrates that one can actually generate
electricity using an electret.  The energy that one generates, however, is
due to the work of bringing the metal plate near to the electret surface,
and then taking it away.  

Thanks for an interesting question.  And if you do make an electret from
granite and barium titanate, send us a picture.