<p>Your rock is probably a piece of a sedimentary concretion.  I have collected rocks that look very similar from western South Dakota.  The yellow crystals are most likely calcite.  The dark brown colored material is also probably calcite and but might be barite.  </p>

<p>Acid testing using HCL should confirm if the yellow and brown area are calcite.
It will probably be difficult to perform an accurate specific gravity measurement for the rock.  My experience is that concretions are commonly quite dense (denser than calcite/dolomite) due to presence of denser minerals such as ankerite, dolomite, barite, celestite, fluorite, marcasite, pyite, sphalerite, siderite, wurzite, and galena as microscopic inclusions hidden within the matrix material.</p>

<p><a href="https://en.wikipedia.org/wiki/Concretion" rel="nofollow noreferrer">Concretions definition from wikipedia.</a></p>

CC BY-SA 4.0
2018-08-06T11:49:23.473Z
2018-08-06T11:49:23.473Z
Earth Science Expatriate
<p>![crystal rock yelowish to red yellow to orange has 3 layers of crystal
)<img src="https://i.sstatic.net/9oTcU.jpg" alt=" both chunks of rock came from the same peace broke of a chunk of the smaller one is one that we started to polish  has sharp crystal edges and it goes right thru the rock in huge vains  "><img src="https://i.sstatic.net/Mkgsl.jpg" alt="found by the river  looks like foam  yellow to dark red orange  3 layers of crystal then rock "></p>

CC BY-SA 4.0
2018-08-03T12:39:58.357Z
The smaler chunk is a peace we broke off and polshied a bit
Matt Woloszyn
CC BY-SA 4.0
2018-08-03T14:37:57.027Z
In which part of the world was it found: country, region, geological setting such as river, mountains, next to the Blue Sky Mine that used to mine gold/zinc/ other metal.
Fred
CC BY-SA 4.0
2018-08-24T11:15:14.090Z
I found it next to the north Saskatchewan river near drayton valley
Matt Woloszyn
<geology>
I found this huge rock crystal by the river have no idea what it is?
Matt Woloszyn
# I found this huge rock crystal by the river have no idea what it is?

(Asked by: username_0 on 2018-08-03)

![crystal rock yelowish to red yellow to orange has 3 layers of crystal
)![ both chunks of rock came from the same peace broke of a chunk of the smaller one is one that we started to polish  has sharp crystal edges and it goes right thru the rock in huge vains  ](https://i.sstatic.net/9oTcU.jpg)![found by the river  looks like foam  yellow to dark red orange  3 layers of crystal then rock ](https://i.sstatic.net/Mkgsl.jpg)

**Tags:** geology

> **Comments:**
> **username_0**: The smaler chunk is a peace we broke off and polshied a bit  
> **username_1**: In which part of the world was it found: country, region, geological setting such as river, mountains, next to the Blue Sky Mine that used to mine gold/zinc/ other metal.  
> **username_0**: I found it next to the north Saskatchewan river near drayton valley  

---

## 1 answers

### Answer by username_2 on 2018-08-06. Score: 2

Your rock is probably a piece of a sedimentary concretion. I have collected rocks that look very similar from western South Dakota. The yellow crystals are most likely calcite. The dark brown colored material is also probably calcite and but might be barite.

Acid testing using HCL should confirm if the yellow and brown area are calcite.
It will probably be difficult to perform an accurate specific gravity measurement for the rock. My experience is that concretions are commonly quite dense (denser than calcite/dolomite) due to presence of denser minerals such as ankerite, dolomite, barite, celestite, fluorite, marcasite, pyite, sphalerite, siderite, wurzite, and galena as microscopic inclusions hidden within the matrix material.

[Concretions definition from wikipedia.](https://en.wikipedia.org/wiki/Concretion)


---

