I received a recommendation from someone who was ejected from here some time ago. For the film Das Blaue Licht directed by and starring Leni Riefenstahl, in 1932 before she got caught up in megalomania.
There's a copy of it on YT - the German-only one is the best quality and the dialogue is so scant as to be barely any trouble if you can muddle through German. Essentially it is a silent film where what would have been inter-titles have just been spoken aloud and there aren't many of them. The musical score is superb and it's been carefully plotted to fit. There's a bit where the 'hero' shouts 'Junta!' (her character's name) and then the musical cue matches it tonally. The way the music carries the film is what makes more like a silent film. It uses leitmotif, but not in crude sort of way.
The photography is spectacular. So much outside photography in 1932 with those cumbersome cameras and done so well. Some of the set pieces are without doubt on a built set, but it's just seamless. There so much clever use of the landscape and natural elements, The swirling clouds and mists play a role themselves, even at one point where instead of a standard fadeout the camera focuses on a black sky where the last of the travelling cloud disappears into the top corner. The editing is also superior.
The crystal-in-the-caves thing is really like a 'MacGuffin'. The story is many things from many sources. Steeped in Swabian type, central European folklore. Fear of unknowns and imaginary things in dangerous places where village folklore has arisen to make people behave in a precautious way. It's also a bit Gothic, a bit vampire without a vampire.
The character Riefenstahl portrays is like a sort of wolf-child. Though she's practically asexual in the film there is a lyric eroticism about her. I don't think she's beautiful, but she's striking and fascinating to look at. You can tell she's a silent film actress and the same performance style runs through all the characters. I think this is a good thing. It gives the film an other-wordly, ethereal feel, like in Nosferatu, but in that non-pantomime way.
I recommend this film to you if you haven't seen it before.