FMF - Friends of Minerals Forum, discussion and message board

[bob kerr]

I acquired a number of brochantites from Milpillas MX that are heavily coated with "white stuff". thinking first that it may be kaolinite (a clay). I put a specimen in warm/hot water for almost two days, and some white stuff came off but there is still lots remaining (see photo). Probing with a toothpick, I came to the conclusion that it is pretty hard and must be something else - dickite??

Any thoughts as to what this may be and what if anything can be done to remove it without impacting the brochantite?

thanks,
bob

[Jordi Fabre]

Although I have not analyzed them it is commonly said that this white material is Dickite and unfortunately is extremely solid and resistant.
As the Brochantite is the opposite ;-) I'm not sure if it exist some way to delete this "white stuff" coating.

[bob kerr]

I think you are correct Jordi. by the way, I asked this question on mindat and received a number of responses and thoughts. you can see them at:
https://www.mindat.org/mesg-19-369386.html

bob