<p>The main hard rock sources of diamonds are either <a href="https://en.wikipedia.org/wiki/Kimberlite" rel="noreferrer">kimberlites</a> or <a href="https://en.wikipedia.org/wiki/Lamproites" rel="noreferrer">lamproites</a>.</p>

<p>Many kimberlite and lamproite deposits occur as:</p>

<blockquote>
  <p>carrot-shaped, vertical intrusions termed 'pipes'</p>
</blockquote>

<p>As the term "carrot-shaped" suggests, the general shape of the <a href="https://en.wikipedia.org/wiki/Volcanic_pipe" rel="noreferrer">pipes</a> is conical and when viewed in horizontal cross-sections they are generally quasi-circular.</p>

<p><a href="https://i.sstatic.net/w3Ld2.jpg" rel="noreferrer"><img src="https://i.sstatic.net/w3Ld2.jpg" alt="enter image description here"></a></p>

<p>When such structures are mined by open cut methods, as with open cut mines of <a href="http://www.thefreedictionary.com/tabular" rel="noreferrer">tabular</a> orebodies it is impossible to mine any open pit to any great depth with vertical walls for ground stability reasons. The mine walls are stepped and the parts of the walls between the horizontal steps are sloped. Because of this, open pit mines start out wide at the top, on the surface, and they get narrower with depth.</p>

<p>If the deposit being mined has a quasi-circular horizontal cross-section and is shaped something like a carrot then the open cut mine will also be conical or quasi-conical in shape.</p>

CC BY-SA 3.0
2017-08-05T15:40:48.330Z
I see. There's really no way around it, it's going to be a cone. Thanks!
uhoh
CC BY-SA 3.0
2017-10-11T04:28:14.027Z
I'm not sure why I hadn't accepted earlier. This is exactly what I was looking for.
uhoh
CC BY-SA 3.0
2017-08-05T15:23:38.003Z
2017-08-05T15:23:38.003Z
Fred
<p>From the BBC's <a href="http://www.bbc.com/news/world-europe-40836301" rel="nofollow noreferrer">Russia: Eight missing in flooded diamond mine</a>:</p>

<p><a href="https://i.sstatic.net/BuTCv.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/BuTCv.jpg" alt="enter image description here"></a></p>

<mining><diamond>
Why do diamond mines seem to always appear conical? Are the above-ground mines all that way? All at about the same angle?
uhoh
# Why do diamond mines seem to always appear conical? Are the above-ground mines all that way? All at about the same angle?

(Asked by: username_0 on 2017-08-05)

From the BBC's [Russia: Eight missing in flooded diamond mine](http://www.bbc.com/news/world-europe-40836301):

[![enter image description here](https://i.sstatic.net/BuTCv.jpg)](https://i.sstatic.net/BuTCv.jpg)

**Tags:** mining, diamond


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## 1 answers

### Answer by username_1 on 2017-08-05. Score: 7 | Accepted answer

The main hard rock sources of diamonds are either [kimberlites](https://en.wikipedia.org/wiki/Kimberlite) or [lamproites](https://en.wikipedia.org/wiki/Lamproites).

Many kimberlite and lamproite deposits occur as:

> carrot-shaped, vertical intrusions termed 'pipes'

As the term "carrot-shaped" suggests, the general shape of the [pipes](https://en.wikipedia.org/wiki/Volcanic_pipe) is conical and when viewed in horizontal cross-sections they are generally quasi-circular.

[![enter image description here](https://i.sstatic.net/w3Ld2.jpg)](https://i.sstatic.net/w3Ld2.jpg)

When such structures are mined by open cut methods, as with open cut mines of [tabular](http://www.thefreedictionary.com/tabular) orebodies it is impossible to mine any open pit to any great depth with vertical walls for ground stability reasons. The mine walls are stepped and the parts of the walls between the horizontal steps are sloped. Because of this, open pit mines start out wide at the top, on the surface, and they get narrower with depth.

If the deposit being mined has a quasi-circular horizontal cross-section and is shaped something like a carrot then the open cut mine will also be conical or quasi-conical in shape.

> **Comments:**
> **username_0**: I see. There's really no way around it, it's going to be a cone. Thanks!  
> **username_0**: I'm not sure why I hadn't accepted earlier. This is exactly what I was looking for.  

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