streak line with scriber pen

maybe it works, maybe it doesnt. Ive never heqr of scribing rocks except for comparing hrdnesses. However,You cannot assign success to your method by not even having some comparison data.(maybe theres a reason for a lack of Wiki entries on using a scribing point to develop an erzats "streak")

Id start with a known mineral that develops a good streak (like hematite ). Do an actual streak test n then compare the color you get from scribing. Are they comparable?

The thing about streak testing is that we have a certain amount of white porcelain ground with which to evaluate the color

It is teached in my "ore resources" course to help identify small minerals in an ore sample when they are too small to use the "porcelain scratch" method.

With the scribing method, "every" silicate and calcerous rocks gives a white line which is coherent with the streak line (so far for what I've compared)
For oxyde and sulfure I don't have made much comparison so I can't tell for sure.

The fact that there is nothing on the web about that and that you haven't heard at all about it make me wonder a lot...

But anyway thanks a lot for your quick answer and have a nice weekend

Ive been an econ geologist involved in field campaigns where the simplest Identification tricks like streak, ignition, or acidification or other means is what we rely upon. The old tricks are often all we have.
Good luck in your studies.

Remember the mathematical relationship for exploration geology,
"The Size of a hand sample is inversely proportional to the distance from the car"

"except if you have a benevolent student to carry your sample. Then it become proportional to that student motivation and how much he holds on that "beer" your promised him"