<ol>
<li>It's white, so the streak colour is obvious.</li>
<li>It's hard. Porcelain is made from aluminosilicates like sillimanite and mullite. Mohs hardness is around 7. Not many geological materials are harder than it, and streak is not a diagnostic feature for those that are harder.</li>
<li>It's rough (i.e. unglazed) so it's really good in breaking tiny fragments from the tested material, thus producing the streak.</li>
<li>It's cheap and widely available.</li>
</ol>

CC BY-SA 3.0
2018-03-30T19:34:48.330Z
Thank you for the quick reply! Would you also happen to know of other  materials that fulfil all or most of your above mentioned criteria and could thus be a good choice as well, or is the popularity of Porcelain so overarching that there is no need for any alternative?
vshlrnjth
CC BY-SA 3.0
2018-03-31T04:44:13.740Z
@vshlrnjth frosted glass maybe? But porcelain is cheaper and not as brittle. Another option could be “porcelain” made of pure alumina, but I don’t think they would be as cheap and widely available as aluminosilicate porcelain.
Gimelist
CC BY-SA 3.0
2018-03-31T06:21:30.347Z
you can use a ceramic wetstone but this is expensive and the color can be a problem.
trond hansen
CC BY-SA 3.0
2018-04-02T22:06:09.157Z
You can also use a hammer to pound the specimen to a powder then look at it on a white piece of paper
haresfur
CC BY-SA 3.0
2018-03-30T14:23:05.013Z
2018-03-30T14:23:05.013Z
Gimelist
<p>What characteristics does Porcelain possess that makes it a good choice for the Streak test?
Additionally, are there any other materials that could also be used for designing a Streak plate?</p>

<geology>
What is the motivation behind the choice of unglazed Porcelain as a Streak plate?
vshlrnjth
# What is the motivation behind the choice of unglazed Porcelain as a Streak plate?

(Asked by: username_0 on 2018-03-30)

What characteristics does Porcelain possess that makes it a good choice for the Streak test?
Additionally, are there any other materials that could also be used for designing a Streak plate?

**Tags:** geology


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## 1 answers

### Answer by username_1 on 2018-03-30. Score: 5

1. It's white, so the streak colour is obvious.
2. It's hard. Porcelain is made from aluminosilicates like sillimanite and mullite. Mohs hardness is around 7. Not many geological materials are harder than it, and streak is not a diagnostic feature for those that are harder.
3. It's rough (i.e. unglazed) so it's really good in breaking tiny fragments from the tested material, thus producing the streak.
4. It's cheap and widely available.

> **Comments:**
> **username_0**: Thank you for the quick reply! Would you also happen to know of other  materials that fulfil all or most of your above mentioned criteria and could thus be a good choice as well, or is the popularity of Porcelain so overarching that there is no need for any alternative?  
> **username_1**: @username_0 frosted glass maybe? But porcelain is cheaper and not as brittle. Another option could be “porcelain” made of pure alumina, but I don’t think they would be as cheap and widely available as aluminosilicate porcelain.  
> **username_2**: you can use a ceramic wetstone but this is expensive and the color can be a problem.  
> **username_3**: You can also use a hammer to pound the specimen to a powder then look at it on a white piece of paper  

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