The Rockies’ infield isn’t 24 karat, but it’s pretty darn golden. Save for one position.

Third base? Glittering. Five-time Gold Glover and perennial MVP candidate Nolan Arenado roams there.

Shortstop? Promising. Trevor Story has terrific potential, now if only he can cut down on the ugly 38 percent strikeout rate that led a National League high 191 whiffs in 2017.

Second base? In good hands. DJ LeMahieu slashed .310/.374/.409 and won his second Gold Glove. Some National media pundits slammed his selection to the All-Star Game, but it was his peers who voted him in, and they know how valuable he is his team.

First base? Here’s where we find the huge question mark. Indeed, it ranks as the club’s biggest puzzle as spring training draws near.

Veteran Mark Reynolds manned the post with aplomb last season (and hit 30 homers), but he remains a free agent, although he’s said he wants to return to Colorado, at the right price. And while the winter rumor mill linked the Rockies to everyone from Carlos Santana (who signed with Philadelphia), to Eric Hosmer, to Logan Morrison, the Rockies have not made a move yet.

So where does that leave them? That question might not be solved until spring training wraps up.

It could be that Ian Desmond, who’ll make $22 million this season as Colorado’s highest-paid player, will take over first base. That’s the primary position general manager Jeff Bridich assigned Desmond after signing him to a five-year, $70 million contract last winter.

Anyway you slice it, Desmond’s first season in Colorado was a major disappointment. He opened the season on the disabled list after breaking his left hand late in spring training, and then a nagging right calf strain landed him on the disabled list twice during the season. All told, Desmond, considered something of an iron man during his career, played in just 95 games and hit .274 with seven homers and a sluggish .375 slugging percentage.

Desmond is perhaps the Rockies’ best all-around athlete, but he never looked entirely comfortable at first base. In fact, he played better in left field, where he started 64 games, than he did at first, where he started 22.

Still, at the winter meetings in December, Bridich tried to put a positive spin on the situation.

“(Desmond’s) more versatile than he was, which is great,”  Bridich said. “I think he showed he can play the outfield, but it was tough for him because he was hurt.”

As for Desmond’s disappointing season, Bridich said: “Some of it was bad luck and some of it was dealing with an injury he’s not used to having. He was not accustomed to missing much time. He and I joked about it at times out of sheer frustration.”

McMahon is also raw at first base. He made his major-league debut last August, but saw limited playing time, batting .157 (3-for-19) in just 17 games. His natural position is third place, a position he played in high school, but he saw playing time at first and second last season in the minors, hitting a combined .355 at Double-A and Triple-A.

“I feel really good and really comfortable at first, and I’ve been working out there all offseason,” McMahon said recently.

Super utility player Pat Valaika is also preparing to play first base, if he’s needed there, but right now the position.

Player Profiles

— Arenado:  He wasn’t a finalist for National League MVP, but he should have been. He set career highs in hits (187), triples (seven), batting average (.309), on-base percentage (.373) and slugging percentage (.586).  He slugged 37 home runs (19 at home, 18 on the road), tied his career high with 43 doubles and drove in 130 runs.

Arenado led all major-league third baseman with 20 defensive runs saved, and he led NL third baseman in total chances (423), assists (311) and double plays (39). He tied for first in fielding percentage, committing only nine errors in 423 total chances (.979 percentage).

He’s scheduled to become a free agent after the 2019 season.

— Desmond: He did give the slow-footed Rockies some speed on the basepaths, leading the club with 15 stolen bases in 19 attempts, and his 22 infield hits were tied for sixth in the NL. But that was negated by Desmond’s overall .627 groundball percentage. Wherever he ends up playing, the Rockies need more production.

— LeMahieu: Led all NL second baseman in total chances (720), assists (470), double plays (107) and fielding percentage (.989). He also hit  .310, feasting off left-handers (.362, the sixth-highest average in the majors). From June 15 to the end of the season, the second baseman’s .335 average ranked first in the National League.

LeMahieu is scheduled to become a free agent after this season, which is why you will see a lot of No. 1 prospect Brendan Rodgers, as well as McMahon, getting time at second during Cactus League games.

— Story: Manager Bud Black touted him for a Gold Glove and Bridich praised Story for his ability to keep his offensive woes separated from his on-field duties. Story’s 1.8  defensive WAR ranked sixth among NL position players.

Story has immense power. Despite a terrible first half, he still hit 24 home runs and drove in 82 runs. Despite his troubling strikeout rate, he showed better strike-zone discipline as the season progressed, and he looked like a more efficient offensive force during a 10-game hitting streak from Sept. 9-19, during which he batted .333, with five doubles, one triple and two home runs.

To Story’s credit, he never allowed his offensive slump (.224 average before the All-Star Game) to leak into his defense. His 11 defensive runs saved were second most in the majors among shortstops, and according to Baseball Reference, he ranked sixth among NL position players with 1.8 defensive WAR.

— Valaika: Last season, Valaika started 16 games at shortstop, five at third base, three at second, two games in left field and one at first. He could see more time at first, and could even be used more in the outfield. He projects as Black’s super-utility player.

He was the Rockies’ best pinch hitter, leading all big-league pinch hitters in RBIs (16), runs (12), doubles (eight) and extra-base hits (12). He figures to be a key part of the team in 2018.

— McMahon: All eyes will be on the rookie this spring. Said Bridich:  “Does he have the tools and the talent to be thought of as our starting first baseman? I think so.”

There is reason to believe in McMahon, both on the bag and at the plate. In 314 plate appearances with Triple-A Albuquerque, McMahon slashed .374/.411/.612 with 39 extra base hits, including 14 homers. Last year in the minors, McMahon split time between first base (61 games), second (36), and third (26). Despite his various duties, McMahon committed only 12 errors, down from the 24 he made in 2016.

— Others to watch: Rodgers, a shortstop by trade, got an invite to big-league camp and will garner a lot of attention. There is a chance he’ll make his debut in the second half of the season. Rodgers will be joined by these other invitees: Daniel Castro, Garrett Hampson, Brian Mundell and Shawn O’Malley.

Up next: The bullpen