@SrRochardBunson @ClaraListensprechen@universeodon.com @Ralph058 @sergio_101 Yes. Mica (the mineral, but carefully selected sheets of it) has been used for like 100 years to make capacitors. No capacitor dielectric can equal its performance, yet.

These fabulous characteristics of mica used to be very important in the design and manufacture of "analog" radios. Their importance is far less today for two main reasons. Modern radio designs don't depend on capacitor performance to maintain frequency stability. 1) We use digital methods to produce extremely precise frequencies locked to a quartz crystal reference. 2) Transmitters are solid state and run on low voltages so the high voltage capability of mica is unimportant. You can use any old material for coupling caps.

Mica still shines in certain niche applications like high powered radio transmitters like 250 kW and 500 kW shortwave transmitters. Those still use vacuum tubes that are supplied with 10,000 to 15,000 volts at 10, 20, 30 amps. Here you'll find mica caps. Some are the size of a basketball and weigh 25 pounds.

@shuttersparks @SrRochardBunson @ClaraListensprechen @Ralph058 @sergio_101 I live in Chennai, India. In my childhood days (a long time ago), I remember visiting a town in neighbouring Andhra Pradesh, called Nellore, which was noted for its mica mines. The owners of these mines were, as always, incredibly wealthy people. I was fascinated by how mica was organised as delicate sheets that you could tease apart. I wonder what has happened to these mines.