Parabutlerite ?

[www.mindat.org] Even though the sample has had a lot of work done on it, it seems to me that I can see a good cleavage! Wouldn't that make this sample Butlerite? The color and crystal habit also suggest Butlerite not Parabutlerite.

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The parabutlerite has been identified by SXRD and several other methods, see updated photo caption.

Thank you Uwe, however I would have been happier with a response like " we had a close look at the sample and what appears to be a good cleavage is not". If in fact it does have a good cleavage then the literature should be updated. I found a similar thing with a specimen of anilite from Michigan. The sample had a perfect cleavage but the published literature says ( and still does) that it has no cleavage so I sent a sample to George Robinson. George was also puzzled by the cleavage, but XRD & probe work confirmed that it was anilite! One other thing, Palache et al. states that Butlerite and Parabutlerite have been found as parallel intergrowths, I wonder if that was taken into consideration.

The anilite cleavage issue might be a case of a pseudomorph after an originally platy material (copper sulphide) with good cleavage.

"... however I would have been happier with a response like " we had a close look at the sample and what appears to be a good cleavage is not". "
?

Cleavage can be influenced by chemical composition, mechanical stress, p/T conditions, exsolution lamellae, etc. Furthermore, there can be confusion with parting. If you ask different people to define "perfect" or "distinct" cleavage, you will get different answers.
Bottom line is, I wouldn't put much emphasis on cleavage as a reliable property for identification.

Hello Uwe,

With respect to the anilite, these are cleavages created by a fresh break of an anhedral grain repeated dozens of times, if you would like a sample to try it yourself I can send you one.