they look and appear heavy and well made

My pink boots have a little more camo pattern than in the picture. The shade of pink is slightly softer, which I prefer, it tones well with the print. I use them for working in the yard when it is mucky out. They are very comfortable and cute.
Highly recommend.

What are mining boots?
If the average/general work boot is the equivalent of a backpacking hiking boot, then mining boots are mountaineering boots. They're more rugged, robust, protective (and heavier) than your general work boot. However, these Ranger mining boots are entry-level mining boots, that costs much - MUCH less than full-featured mining boots. Basically, these Ranger mining boots are a more rugged, thick, robust (and possibly heavier) version than the typical rain work boot.

What do more expensive non-mining, rubber work boots offer?
Comfort, likely; since they are likely to be lighter weight and more flexible. A higher shaft.

What do more expensive mining boots offer?
Metatarsal protection, a shank, more rugged outsole, better whole-boot puncture/cut resistance, increased resistance to harsh chemicals, better hi-viz features, laces/zippers, and other bells and whistles.

My review:
For reference, I have borderline wide feet with narrow heels, I occasionally resort to wide sizes for a comfortable fit, but not always. I almost universally wear size 10 in all my footwear, however, in rare instances I resort to size 10.5 or 11, because of toe box issues or a wider size is not offered. These boots at size 10 are true-to-fit; they accommodate my wide-ish feet without any pressure points.

It was such perfect timing when these boots arrived, as I just got assigned to operate a dust-control, water truck, so muddy puddles, along with sharp rocks was to be in the equation.

On my first day wearing them, I wore non-cushioned midweight socks. I experienced a little bit of heel slop (I have narrow heels), but it was tolerable and not distracting. After an 8 hour shift my feet were tired, but not sore, nor achy. Although, the boot has a separate heel, I felt that my balls of my feet were more elevated than my heels; a weird sensation at first, but I soon got used to it. The steel-toe protection doesn't pinch my toes with mild toe flexing, unless I kneel with my toes fully bent.

On my second day, I wore cushioned midweight socks (made specifically for steel-toe footwear), and there was a significant improvement in comfort and fit (decreased heel slippage), so I highly recommend cushioned socks if one experiences tiredness or slippage with non-cushioned socks. However, even with cushioned socks these boots won't be my daily, go-to boots if I won't encounter mud, they don't surpass the comfort of good quality leather work boots in non-muddy settings.

These boots didn't accommodate heavyweight/thermal socks on my feet. Up-sizing wouldn't work, as the boot is too narrow to accommodate thermal socks on my already wide-ish feet.

I think these boots are excellent for wet/muddy environments that include sharp/abrasive surfaces (as in mines, etc.). At Sierra's pricing, these boots are an excellent value, since there are non-mining, safety-toed "gum" work boots at higher prices.

Things to consider:
It appears these boots don't have shanks. Sierra's description doesn't mention it, and I can observe some lateral flexing on the boots.

I also bought Georgia Boot Muddog Wellington Work Boots here at Sierra (currently offered at the time of writing this review). I'd say these Ranger boots are a better buy and better value than the Georgia boots for muddy conditions.The Ranger boots were true-to-fit, more comfortable, and by subjective assumption, possibly will be more durable.

These boots are easier to clean and upkeep in muddy conditions (ESPECIALLY with wet clay) than waterproof leather boots. No routine soaping, nor oiling necessary. (However, since rubber is more sensitive to sun exposure damage than leather, I recommend routine coating with rubber protector or Aerospace 303 spray depending on sun exposure frequency).

May not be suitable for wet, slick, slippery, smooth surfaces (like food/meat processing plants, boats, etc.), since the outsole is mildly lugged without any sipping. (You want sipes, not lugs for those slippery surface conditions).

These boots may be overkill for light-duty use, like gardening, ranching, etc. The rubber construction is slightly thicker than other rubber/pvc work boots making them a bit heavier and stiffer than other "gum" boots.

They have reflective patches that actually reflect in low light conditions!

May be too heavy for some. It wasn't an issue for me. I measured 7.5 lbs for both boots on a bathroom scale (3.75 lbs for each boot).

Potential heel slippage may be annoying or distracting, especially for those who don't wear pull-on work boots. There are lace-up mining boots offered elsewhere.

Since they're lined with thin layer of neoprene, they can be used as mild winter boots (avoiding icy surfaces). However, because of the neoprene interior and black rubber exterior, they start feeling uncomfortably hot above temperatures of ~85F.

These boots are not a solid, one-piece of molded rubber. The outsole is glued on to the boot, which can be a problem if the boot is heavily stressed or exposed to solvents.

Overall, I'm satisfied with these boots, they won't replace my leather boots, but for muddy and rocky terrain, they'll be my go-to boots.