<p>In the geologic sense of the word, rocks or stones are made up predominantly of inorganic minerals. There certainly are rocks like some limestones that contain a large proportion of biogeochemically produced minerals like shells or later alteration of the original biological material. Some rocks may contain some organic matter but it often doesn't survive the process of compacting and lithifying (turning into rock).</p>

<p>However, from the Wiki page, it sounds like gall stones are dominantly organic matter like cholesterol that may contain some inorganic material like calcium phosphate or calcium carbonate. So I wouldn't really consider them stone in the sense used in earth science but maybe there could be some gall stones that get trapped in sediments after a person dies and then turn into a tiny proportion of a sedimentary rock.</p>

CC BY-SA 3.0
2017-05-28T23:39:31.980Z
2017-05-29T01:34:37.397Z
2017-05-29T01:34:37.397Z
haresfur
<p>"Metamorphic rocks arise from the transformation of existing rock types"
"a natural substance, a solid aggregate of one or more minerals or mineraloids."</p>

<p>Looks like Metamorphic wins. </p>

CC BY-SA 4.0
2019-06-12T23:07:07.790Z
2019-06-12T23:07:07.790Z
user17114
<p>The nature of this question is more about biological chemistry than it is about earth science. This is because gall stones have nothing to do with geology, but chemical processes in the body.</p>

<p>Consequently, it would be inappropriate to apply geological classifications, such as igneous, sedimentary or metamorphic, to gall stones.</p>

<p>Due to the way gall stones are formed - layers of bile coating a nucleus - they could be describes as being <a href="https://en.wikipedia.org/wiki/Concretion" rel="noreferrer">concretions</a>. </p>

CC BY-SA 3.0
2017-05-26T12:39:29.093Z
I suppose a body's stone really isn't ALL that different from sedimentary silting.  It's definitely not a result of temperature and pressure!
JeopardyTempest
CC BY-SA 3.0
2017-05-26T11:59:31.070Z
2017-05-26T11:59:31.070Z
Fred
<p>From <a href="https://en.m.wikipedia.org/wiki/Rock_(geology)" rel="nofollow noreferrer">Wikipedia</a>:</p>

<blockquote>
  <p>Rock or stone is a natural substance, a solid aggregate of one or more minerals or mineraloids. For example, granite, a common rock, is a combination of the minerals quartz, feldspar, and biotite. The Earth's outer solid layer, the lithosphere, is made of rock.</p>
</blockquote>

<p>From <a href="https://en.m.wikipedia.org/wiki/Gallstone" rel="nofollow noreferrer">Wikipedia page about gallstones</a>:</p>

<blockquote>
  <p>A gallstone is a <strong>stone</strong> formed within the gallbladder out of bile components</p>
</blockquote>

<p>So if rocks are stones, what type of rock are gallstones?</p>

<ul>
<li><p>Igneous rock is formed through the cooling and solidification of magma or lava.</p></li>
<li><p>Sedimentary rocks are types of rock that are formed by the deposition and subsequent cementation of that material at the Earth's surface and within bodies of water. </p></li>
<li><p>Metamorphic rocks arise from the transformation of existing rock types, in a process called metamorphism</p></li>
</ul>

<p>Gallstones don't fit into any of these categories so <strong>what type of rock is it?</strong></p>

CC BY-SA 3.0
2017-05-26T12:38:02.597Z
Could also reasonably call it an English question or an example of using a less sharp definition.  [Simple Wiki says](https://simple.m.wikipedia.org/wiki/Tree) a tree is a tall plant with a trunk and branches made of wood.  Doesn't mean a family tree is such a plant :-).  Indeed, sources that aren't true full dictionaries will pass on non pertinent definitions.  Doesn't make the word valid.  If you wanted to ask on the English SE, they might well be able to explain where the connection first came about
JeopardyTempest
CC BY-SA 3.0
2017-05-27T05:47:41.310Z
@JeopardyTempest: For instance, it's common (at least in gardening circles) to talk of "stone fruit" like peaches & plums, which have a hard stone or pit in the center, even though that "stone" is vegetable rather than mineral.
jamesqf
<geology><rocks><terminology>
If rocks are stones, what type of rock are gallstones?
Muslim_1234
# If rocks are stones, what type of rock are gallstones?

(Asked by: username_0 on 2017-05-26)

From [Wikipedia](https://en.m.wikipedia.org/wiki/Rock_(geology)):

> Rock or stone is a natural substance, a solid aggregate of one or more minerals or mineraloids. For example, granite, a common rock, is a combination of the minerals quartz, feldspar, and biotite. The Earth's outer solid layer, the lithosphere, is made of rock.

From [Wikipedia page about gallstones](https://en.m.wikipedia.org/wiki/Gallstone):

> A gallstone is a **stone** formed within the gallbladder out of bile components

So if rocks are stones, what type of rock are gallstones?

* Igneous rock is formed through the cooling and solidification of magma or lava.
* Sedimentary rocks are types of rock that are formed by the deposition and subsequent cementation of that material at the Earth's surface and within bodies of water.
* Metamorphic rocks arise from the transformation of existing rock types, in a process called metamorphism

Gallstones don't fit into any of these categories so **what type of rock is it?**

**Tags:** geology, rocks, terminology

> **Comments:**
> **username_1**: Could also reasonably call it an English question or an example of using a less sharp definition.  [Simple Wiki says](https://simple.m.wikipedia.org/wiki/Tree) a tree is a tall plant with a trunk and branches made of wood.  Doesn't mean a family tree is such a plant :-).  Indeed, sources that aren't true full dictionaries will pass on non pertinent definitions.  Doesn't make the word valid.  If you wanted to ask on the English SE, they might well be able to explain where the connection first came about  
> **username_2**: @username_1: For instance, it's common (at least in gardening circles) to talk of "stone fruit" like peaches & plums, which have a hard stone or pit in the center, even though that "stone" is vegetable rather than mineral.  

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## 3 answers

### Answer by username_5 on 2017-05-26. Score: 5 | Accepted answer

The nature of this question is more about biological chemistry than it is about earth science. This is because gall stones have nothing to do with geology, but chemical processes in the body.

Consequently, it would be inappropriate to apply geological classifications, such as igneous, sedimentary or metamorphic, to gall stones.

Due to the way gall stones are formed - layers of bile coating a nucleus - they could be describes as being [concretions](https://en.wikipedia.org/wiki/Concretion).

> **Comments:**
> **username_1**: I suppose a body's stone really isn't ALL that different from sedimentary silting.  It's definitely not a result of temperature and pressure!  

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### Answer by username_3 on 2017-05-28. Score: 0

In the geologic sense of the word, rocks or stones are made up predominantly of inorganic minerals. There certainly are rocks like some limestones that contain a large proportion of biogeochemically produced minerals like shells or later alteration of the original biological material. Some rocks may contain some organic matter but it often doesn't survive the process of compacting and lithifying (turning into rock).

However, from the Wiki page, it sounds like gall stones are dominantly organic matter like cholesterol that may contain some inorganic material like calcium phosphate or calcium carbonate. So I wouldn't really consider them stone in the sense used in earth science but maybe there could be some gall stones that get trapped in sediments after a person dies and then turn into a tiny proportion of a sedimentary rock.


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### Answer by username_4 on 2019-06-12. Score: -1

"Metamorphic rocks arise from the transformation of existing rock types"
"a natural substance, a solid aggregate of one or more minerals or mineraloids."

Looks like Metamorphic wins.


---

