No, Large is a big deal
The Constitution bonus is really rather high, and the Dexterity defecit is fairly negligible when compared to the natural armor. I'd do a +3 Con, -1 Dex, -1 Cha to make it a little more rounded.
Do NOT mess around with larger sizes. It has major implications that even the devs don't want to touch. You can borrow the Goliath's size option, which simply makes them lift as though they were larger.
Speed of 15 is a major problem. The party will not have a good time trying to drag you around from place to place, especially if you're too heavy for a horse.
Natural Armor is a bit too high, unless you were trying to make this thing not wear armor.
Acid resistance isn't too bad. Resistances are rare among PC races, but not unheard of.
Brittle is not very good, due to fall damage being very rare, and it doesn't quite describe how the 50% works. Rounded up or down?
The Sight issue will keep them from being a spellcaster without additional information. Most spells rely on sight, and a sight of 10 feet...well, you get the idea.
Innate spellcasting is mostly okay. Earthquake is a nice spell, but likely nobody will ever see it as it's a level 20 requirement. I'd recommend lowering the Earthquake requirement, replacing the Earthquake with other low level spells, like with the Tiefling. Thunderwave, Earth Tremor, Meld Into stone, stuff like that.
The main concern with this thing (besides size) is that no class really benefits from being a Terran.
Warrior classes are valued because of their armor benefits and versatility, where this class already grants you the equivalent of heavy armor and hurts versatility (with no eyesight and speed).
Spellcasters and ranged fighters wouldn't be able to fight or use magic without a LOT of game breaking.
Rogues would be far too slow with poor stats.
Natural armor doesn't stack with unarmored defenses, which limits how effective choosing a barbarian or monk would be.
MAYBE I'd play a melee warlock, if only because these things are indestructible, and I can just cherry pick spells that center on me or use melee attacks. But that character would be crazy strong.