I didn't notice i would have created that confusion regarding Thanjavur paintings. It occurred to me only now when I read your recalling our dialogue.
let me turn to your questions.
Question one: I've heard that Ajantha paintings are luminous and some of them can glow even without much light. Is that true ?
Answer: I don't think this is true. I am not aware of any normal mineral pigment that can glow. Nor have I come across with this in any reference on Ajanta paintings. There is possiblility of this kind of opinion because of one of the paintings which have a somewhat different. In Cave 17 there is a famous painting commonly known a 'Lady in her Toilet', which I rename as 'lady doing her make up'. The artist has cleverly used blobs of paint on her necklace. The guide shows a torch at an angle and you have an eerie feeling of depth. May be the myth started from here.
QuestionTwo: How about tanjore temple painting colours ? Were they of organic or based on minerals and rocks ?