![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgblKyqHLSZ1zqw6kEwr1Tf7ZHWzZnFTuJ7OPIVDFSlMqChK0yIXlYK0CCzPPpWVrB8cSNnnXXACbHGc2ZZbByIkQhcjDL62fAcSLgvCCbmZhZvGMCNBGmEujqp_AHYQdgzi6s746hD4T4L/s400/IMG_8447_3_1.jpg)
We saw a lot of rocks and minerals on last month's
field trip to Goldfield, NV. At the second stop, our f.t. leader had laid out a large collection of large rocks on pallets, one row for one area, one row for another. The pallets were then arranged, north to south, by the age of the rocks. I thought it was a great way of arranging the rocks, especially since we didn't have time to go see them all in the field!
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjJ-M3aNFJw0rOsHn-QxNoAOoKmCR8b38Alwo5Vb881aLcTXCPzRcnIBFyBj4R7xZckuKGbfV4i_Ug7zah4YApkRgHhhO5ybUXhugdTkxOI4OzNMzM6fafpnFVTl86jGrTVZQvzyPnjhBCH/s400/IMG_8450_1_2.jpg)
Today's mineral from Goldfield is
alunite, a trigonal, sometimes psuedo-cubic, anhydrous alumino-potassic sulfate. In this photo, it's a hydrothermal, hypogene alteration mineral replacing potassium feldspar in rhyolite.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjwm_XQ8pq3KEJc-QD8rF_W0qwkQ2Fhx9xZbXZAlKzqizZckGud7W2ZukTjfehEt_aveX9B-04jSkC3XSxLkOVVGOyNScAfukhrXGyRvWMSyuVrgaL0PElPvt-LdT-QpYV9M7M0M3hSL7Sz/s400/IMG_8450_2_1.jpg)
Goldfield has some of the nicest alunite I've seen, with a classic pink color, although one can also find classic pink alunite at
Alunite, Utah and other places.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgxn2u04djKYORhrsK8oiw7igqXY6L7kGvDd-7zrXduohSxpBqks7vA8A3RXEr6uVeeZw7-Jrq63KktILeRVZPYp3p6mNkRG4DKUYIolSiGrAfrhcD_Ffk0n1UqVGgLY1eEBkSuMSR07yBF/s400/IMG_8456_1_2.jpg)
More alunite, still pinkish, and showing its classic tabular crystal form.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgXud5I-9efzY8wY8AI8m1shcTD0Gu1a6oBpzLbYo39aZpVJA7unFfPVdssree-FG16Bh95QenJ6U2AAIo7jE9ekDOL0MEIgNCMi7XDnnQtbDHygfzz2erJx1bOp-IRRhg4q5S0tJK7Bw8S/s1600/IMG_8457_2_1.jpg)
If you see a mineral with this shape, think
alunite. It's not always pink (or reddish); it can be colorless, white, gray, to yellowish. The supergene form is often massive, looking somewhat like
jarosite.
2 comments:
Nice shots of the minerals!
Thanks, Anon, whoever you might be! :)
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