Page 1 of 1

A source for diatoms

Posted: Mon Dec 09, 2019 8:01 pm
by Microworld Steve
Is this kind of diatomaceous earth a good source for finding diatoms for mounting on slides? :?:
41-jQMcvxyL._AC_.jpg
41-jQMcvxyL._AC_.jpg (23.09 KiB) Viewed 3782 times

Re: A source for diatoms

Posted: Mon Dec 09, 2019 8:56 pm
by MicroBob
Hi Steve,
whether you will find complete diatom frustures or not varies from product to product. As this is no defined property of the product it may vary too. Generally you have to expect lots of broken bits and an intact diatom here and there. Especially the bigger diatoms will be broken most of the time.

Have you already tried to collect diatoms yourself? Do you have a mounting medium for them?

Bob

Re: A source for diatoms

Posted: Mon Dec 09, 2019 9:12 pm
by Microworld Steve
MicroBob wrote:
Mon Dec 09, 2019 8:56 pm
Hi Steve,
whether you will find complete diatom frustures or not varies from product to product. As this is no defined property of the product it may vary too. Generally you have to expect lots of broken bits and an intact diatom here and there. Especially the bigger diatoms will be broken most of the time.

Have you already tried to collect diatoms yourself? Do you have a mounting medium for them?

Bob
Hi Bob, That's the same thing that I was thinking. The process from mining to packing, to selling probably takes it's toll on the diatoms.

No, I haven't tried to collect any, I really don't know much about finding them. I do have a couple types of mounting mediums I use.

Re: A source for diatoms

Posted: Tue Dec 10, 2019 12:21 am
by MicroBob
Diatoms can be found in different places so why not start with something simple. When you scrape of the slime film on water plants you will usually find diatoms, and not too much dirt. Then you place some diatom slime on a cover slip, place the cover slip on a piece of flat stainless steel sheet metal and heat it to ca. 450 °C for a couple of minutes. Organic matter is oxidized and the relatively clean frustules remain. Diatoms have a refractive index of ca. 1,42. For good visiblity you need a mountant with an r.i. that differs by at least 0,1 from this value. Usually mountants like Pleurax or Naphrax are used, but you can simply use air with it's r.i. of 1! So just attatch the cover slip dry to a slide with a bit of glue at the edges and start observing. Here in Germany it is nearly winter now and the diatoms may be more difficult to find than in summer.

Bob

Re: A source for diatoms

Posted: Tue Dec 10, 2019 1:26 am
by KurtM
Bob is giving excellent advice. I can only add that a series of three short Youtube videos have inspired several of us to delve more into this fascinating subject.

https://www.youtube.com/watch?v=NrhSqu8YCBo

Re: A source for diatoms

Posted: Tue Dec 10, 2019 1:59 am
by Microworld Steve
MicroBob wrote:
Tue Dec 10, 2019 12:21 am
Diatoms can be found in different places so why not start with something simple. When you scrape of the slime film on water plants you will usually find diatoms, and not too much dirt. Then you place some diatom slime on a cover slip, place the cover slip on a piece of flat stainless steel sheet metal and heat it to ca. 450 °C for a couple of minutes. Organic matter is oxidized and the relatively clean frustules remain. Diatoms have a refractive index of ca. 1,42. For good visiblity you need a mountant with an r.i. that differs by at least 0,1 from this value. Usually mountants like Pleurax or Naphrax are used, but you can simply use air with it's r.i. of 1! So just attatch the cover slip dry to a slide with a bit of glue at the edges and start observing. Here in Germany it is nearly winter now and the diatoms may be more difficult to find than in summer.

Bob
Thanks for the info here Bob. I'll give your advice a try and see what I come up with. :)

Re: A source for diatoms

Posted: Tue Dec 10, 2019 2:00 am
by Microworld Steve
KurtM wrote:
Tue Dec 10, 2019 1:26 am
Bob is giving excellent advice. I can only add that a series of three short Youtube videos have inspired several of us to delve more into this fascinating subject.

https://www.youtube.com/watch?v=NrhSqu8YCBo
Those videos helped a lot. :D

Re: A source for diatoms

Posted: Tue Dec 10, 2019 2:10 am
by MicroBob
Here I posted a picture of a dried out diatom in salt water: viewtopic.php?f=6&t=8130&p=71279&hilit=diatom#p71279
I frequently take a microscope with me when I travel, but here I had to improvise a preparation method and the result was special but interesting.

Re: A source for diatoms

Posted: Tue Dec 10, 2019 2:33 am
by Microworld Steve
MicroBob wrote:
Tue Dec 10, 2019 2:10 am
Here I posted a picture of a dried out diatom in salt water: viewtopic.php?f=6&t=8130&p=71279&hilit=diatom#p71279
I frequently take a microscope with me when I travel, but here I had to improvise a preparation method and the result was special but interesting.
That's a neat picture and it came out really good. Thanks for sharing it.

Re: A source for diatoms

Posted: Sat Dec 14, 2019 2:09 pm
by Radazz
This is what I get from diatomaceous earth.
Olympus BX40. 40x. Phase Contrast
Image
Radazz

Re: A source for diatoms

Posted: Sat Dec 14, 2019 3:08 pm
by MichaelG.
Looks pretty diatomaceous to me !

MichaelG.
.

Edit: Here’s some info. about the Harris product:
https://pfharris.com/products/food-grad ... ous-earth/

Re: A source for diatoms

Posted: Sat Dec 14, 2019 9:44 pm
by MicroBob
Hi together,
the look of the Radazzs diatomaceous earth can also be had when looking at fossile diatom material. I once borrowed a bottle of Oamaru diatoms to prepare slides for a group meeting. This wasn't about diatoms at all, it was about measuring and I needed nice objects of suitable size. My expectations were: Make a strew slide to get to know these great diatom range. The truth was : Lots of bits of great diatoms, only here and there an intact frustule! :shock: I like to use sieves from stainless steel mesh and the simple but unscientific conclusion was to filter out the bigger part.
In this way it might be possible to extract intact frustules from diatomaceous earth.

The big question is: Is it worth the hassle? If diatomaceous earth from exotic locations were availabe - yes. To get a couple of ordinary diatoms in questionable condition- no?

Bob