# Geologists: Care to guess what this rock might be? **URL:** \ **Category:** In My Humble Opinion\ **Created:** [January 16, 2018, 10:18pm UTC](https://boards.straightdope.com/t/geologists-care-to-guess-what-this-rock-might-be/806782 "2018-01-16T22:18:26Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![brujaja](https://avatars.discourse-cdn.com/v4/letter/b/4af34b/32.png) [@brujaja](https://boards.straightdope.com/u/brujaja)\ **Post date:** [January 16, 2018, 10:18pm UTC](https://boards.straightdope.com/t/geologists-care-to-guess-what-this-rock-might-be/806782/1 "2018-01-16T22:18:26Z")
I found it on the shore of the Bay in Emeryville, California. It is a pale and translucent pink. One one side, it is lumpy and appears to have been formed by being molten. On the underside, however, one can see crystalline formations that appear to be cube-shaped. It is very, very hard, defying a dremel with a metal burr. Pictures [here,](https://i.imgur.com/ZEczeP0.jpg) [here,](https://i.imgur.com/jXKKZc0.jpg) [here,](https://i.imgur.com/oHehBn4.jpg) [and here.](https://i.imgur.com/IFJiMfq.jpg) I apologize for my inferior camera. ---
**Author:** ![Ethilrist](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ethilrist/32/4604_2.png) [@Ethilrist](https://boards.straightdope.com/u/Ethilrist)\ **Post date:** [January 16, 2018, 10:39pm UTC](https://boards.straightdope.com/t/geologists-care-to-guess-what-this-rock-might-be/806782/2 "2018-01-16T22:39:49Z")
I think this is how The Blob started… ---
**Author:** ![gnoitall](https://avatars.discourse-cdn.com/v4/letter/g/bb73d2/32.png) [@gnoitall](https://boards.straightdope.com/u/gnoitall)\ **Post date:** [January 16, 2018, 10:49pm UTC](https://boards.straightdope.com/t/geologists-care-to-guess-what-this-rock-might-be/806782/3 "2018-01-16T22:49:30Z")
The color and visible crystal structure remind me of pink K-spar ([orthoclase](https://en.wikipedia.org/wiki/Orthoclase)). In a [granite with pink mineral](https://en.wikipedia.org/wiki/Granite#/media/File:Fj%C3%A6regranitt3.JPG), that’s usually orthoclase. ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [January 16, 2018, 10:49pm UTC](https://boards.straightdope.com/t/geologists-care-to-guess-what-this-rock-might-be/806782/4 "2018-01-16T22:49:46Z")
I’m not a geologist, but I dabbled for a year or two as a kid. It could be a lot of different minerals, but a good guess would be a kind of [feldspar](https://en.wikipedia.org/wiki/Feldspar): > [@](#): > > Feldspars (KAlSi3O8 – NaAlSi3O8 – CaAl2Si2O8) are a group of rock-forming tectosilicate minerals that make up about 41% of the Earth’s continental crust by weight. They definitely come in that shade of pink. If you picked it up on a beach the “molten” appearance is much more likely to be the result of erosion. ---
**Author:** ![Sunny\_Daze](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sunny_daze/32/438_2.png) [@Sunny\_Daze](https://boards.straightdope.com/u/Sunny_Daze)\ **Post date:** [January 16, 2018, 11:23pm UTC](https://boards.straightdope.com/t/geologists-care-to-guess-what-this-rock-might-be/806782/5 "2018-01-16T23:23:16Z")
My vote is granite with vein(s) of pink mineral. ---
**Author:** ![brujaja](https://avatars.discourse-cdn.com/v4/letter/b/4af34b/32.png) [@brujaja](https://boards.straightdope.com/u/brujaja)\ **Post date:** [January 17, 2018, 1:04am UTC](https://boards.straightdope.com/t/geologists-care-to-guess-what-this-rock-might-be/806782/6 "2018-01-17T01:04:03Z")
Well, everyone’s educated guesses here appear to support, at least in part, my original impression that it was a pink moonstone. That particular area is known for having moonstone around; I know a guy who has found many specimens including one or two pretty big ones. Moonstone is what I wanted to find, and specifically went out looking for. (I’d tried this many times before, but never found anything.) But then my best friend told me it can’t be moonstone, because moonstone is relatively soft. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [January 17, 2018, 9:23am UTC](https://boards.straightdope.com/t/geologists-care-to-guess-what-this-rock-might-be/806782/7 "2018-01-17T09:23:46Z")
The colour looks a bit like rose quartz, but that doesn’t often form neat crystals, and when it does, they’re not cubic.