using System;

using System.Linq;

using System.Collections.Generic;

​

public class Program

{

    public static void Main()

    {

        var BoxCoords = new List<double[]>

        {

            new []{8.03698858873275  , -1622.419367705   , 180.603950687759},

            new []{8.03698858855283  , -1622.41905090503 , -220.203952098008},

            new []{-7.70512234523364  , -1665.73116372802 , -220.204298594721},

        };

        var columnMins = BoxCoords

            .SelectMany(bc => bc.Select((v, idx) => new {Idx = idx, Val = v}))

            .GroupBy(up => up.Idx)

            .Select(grp => grp.Min(x => x.Val));    

​

        foreach(var colMin in columnMins) 

        {

            Console.WriteLine(colMin);

        }

    }

}