How about using
https://eddb.io/body ?
Works nice for me, especially if you are looking for more than one material.
Just enter Arsenic in the Material Finder and your currently System under Reference System.
While in SRV you will find the most Arsenic in mettalic meteorite and meserodites. How to identify ? use
http://www.wavescanner.net/ !
Hope that helps...
This is by far the most efficient way that I use to find every material.
I would like to also recommend a method I use to find those deposits
In typical RNG fashion, unless someone has a more concrete method from observed deposit spawns, they are random.
As such I find that the quickest way to find deposits is to land on part of the planet at is as flat as possible. When landing, note the heading that leads you through said flat-area. Once on the ground, check your scanner for and signals and clear those; I have found that it matters very little which deposits you go for - with the exception of metallic meteorites which always have the best chance. Meserodites do seem to have a higher drop chance of the rarer mats, but I have got them from outcrops too.
Once you have cleared the area around your landing site and the scanner returns few or no signals, put your foot down and get on the heading noted when landing. If you just drive straight-ish if you don't spot anything within the first few minutes, just slow down and do a 360. Something is normally there... if not get back onto your heading again. Rince and repeat and you should find plenty of mats.
You may find people recommend landing in craters or in mountainous areas for higher chance of Metallic Meteorites.. Whilst this "may" be true, you can't travel as fast in that hilly terrain - hence the flat land approach.
There does seem to be some correlation with large craters and finding metallic meteors, but in my experience it's not a huge difference. I prefer to search flat areas, where I can cover a lot of ground quickly. That works best for me.
Artigan99 confirms this method.
Good luck.
P.S. If you find a Metallic Meteorite deposit, there is almost ALWAYS three in that area not just one. The other two may not appear as a signal on you scanner, but you should still hear the signal as you pan around. Sometimes even that doesn't hold true, but they are still there. Either get in the turret to look around or go to your debug camera (the new Camera system in 2.3 should help greatly to spot these when released as well (hopefully FDev will have fixed the wavescanner so they do show up)).