français vers anglais Sciences sociales Géologie anthropological artefacts

Same text as the previous question posted, on artefacts to do with rain in different cultures.

minéraux qui, par leur aspect, évoquent la pluie ou les phénomènes météorologiques qui y sont liés : quartz translucide « génie de l’arc en ciel », obsidienne, concrétions de magnésie de Nouvelle Calédonie…

I guess this is something like "rainbow spirit" quartz crystal, but I haven't found anything to corroborate that. This could be posted as two different terms, but I think the whole phrase refers to one object which may be called something completely different in English. Thank you in advance for any ideas.