Happy New Year, April! Hope you're having a good day!
Yes, it's nice that it's warmed enough to go out and play!

Thank you for showing everyone the correct way to post a specimen for identification by including as much information as you can about it and a good picture. Well done!
I'm going to guess it's a small water-rounded cobble of smoky quartz with white lines running through it. I'm sure you've seen larger pieces of it. Yes, some quartz will scratch other quartz.

If you aren't sure, cut that egg in two and we'll see!

Well, Yeah, that yellow is a bit of a surprise!
That's kind of pretty. If it weren't for the fractures that would be nice enough to see what a cab looks like. The yellows are probably caused by iron oxides caught in the quartz.
Keep on hunting and thanks for the pictures!

I need to go find a first-day-of-2023 rock.