diff --git a/Makefile b/Makefile
index 58c3415..89d33bf 100644
--- a/Makefile
+++ b/Makefile
@@ -5,6 +5,12 @@ changeset-dev:
 changeset-test:
 	cd changeset && make test
 
+coordinates-dev:
+	cd coordinates && make dev
+
+coordinates-test:
+	cd coordinates && make test
+
 emseries-dev:
 	cd emseries && make dev
 
diff --git a/coordinates/Cargo.lock b/coordinates/Cargo.lock
new file mode 100644
index 0000000..4aa5567
--- /dev/null
+++ b/coordinates/Cargo.lock
@@ -0,0 +1,325 @@
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+# It is not intended for manual editing.
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diff --git a/coordinates/Cargo.toml b/coordinates/Cargo.toml
new file mode 100644
index 0000000..a5f3e17
--- /dev/null
+++ b/coordinates/Cargo.toml
@@ -0,0 +1,10 @@
+[package]
+name = "coordinates"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+proptest = "1.0"
+thiserror = "1.0"
diff --git a/coordinates/Makefile b/coordinates/Makefile
new file mode 100644
index 0000000..1bd40ea
--- /dev/null
+++ b/coordinates/Makefile
@@ -0,0 +1,9 @@
+
+dev:
+	cargo watch -x build
+
+test:
+	cargo watch -x test
+
+test-once:
+	cargo test
diff --git a/coordinates/src/hex.rs b/coordinates/src/hex.rs
new file mode 100644
index 0000000..3283c21
--- /dev/null
+++ b/coordinates/src/hex.rs
@@ -0,0 +1,163 @@
+/// Ĉi-tiu modulo enhavas la elementojn por kub-koordinato.
+///
+/// This code is based on https://www.redblobgames.com/grids/hexagons/
+use crate::Error;
+use std::collections::HashSet;
+
+/// An address within the hex coordinate system
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct HexAddr {
+    q: i32,
+    r: i32,
+}
+
+impl HexAddr {
+    /// Create a new axial coordinate address.
+    pub fn new(q: i32, r: i32) -> Self {
+        Self { q, r }
+    }
+
+    pub fn origin() -> HexAddr {
+        HexAddr { q: 0, r: 0 }
+    }
+
+    pub fn q(&self) -> i32 {
+        self.q
+    }
+
+    pub fn r(&self) -> i32 {
+        self.r
+    }
+
+    pub fn s(&self) -> i32 {
+        -self.q - self.r
+    }
+
+    /// Get a list of coordinates adjacent to this one.
+    pub fn adjacencies(&self) -> impl Iterator<Item = HexAddr> {
+        vec![
+            HexAddr::new(self.q + 1, self.r),
+            HexAddr::new(self.q, self.r + 1),
+            HexAddr::new(self.q - 1, self.r + 1),
+            HexAddr::new(self.q - 1, self.r),
+            HexAddr::new(self.q, self.r - 1),
+            HexAddr::new(self.q + 1, self.r - 1),
+        ]
+        .into_iter()
+    }
+
+    /// Test whether a coordinate is adjacent to this one
+    pub fn is_adjacent(&self, dest: &HexAddr) -> bool {
+        dest.adjacencies().collect::<Vec<HexAddr>>().contains(&self)
+    }
+
+    /// Measure the distance to a destination
+    pub fn distance(&self, dest: &HexAddr) -> usize {
+        (((self.q() - dest.q()).abs() + (self.r() - dest.r()).abs() + (self.s() - dest.s()).abs())
+            / 2) as usize
+    }
+
+    /// Get an iteration to all of the coordinates within the specified distance of this one.
+    pub fn within(&self, distance: usize) -> impl Iterator<Item = HexAddr> {
+        let eko = self.clone();
+        let mut rezulto: HashSet<HexAddr> = HashSet::new();
+        let mut vico: Vec<HexAddr> = Vec::new();
+
+        vico.push(eko);
+
+        while vico.len() > 0 {
+            let elem = vico.remove(0);
+            for adj in elem.adjacencies() {
+                if self.distance(&adj) <= distance && !rezulto.contains(&adj) {
+                    vico.push(adj.clone());
+                }
+            }
+            rezulto.insert(elem);
+        }
+
+        rezulto.remove(self);
+        rezulto.into_iter()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use proptest::prelude::*;
+    use std::collections::HashSet;
+
+    #[test]
+    fn distance_0_is_empty() {
+        let addr = HexAddr::origin();
+        let lst: Vec<HexAddr> = addr.within(0).collect();
+        assert_eq!(lst.len(), 0);
+    }
+
+    #[test]
+    fn distance_1_has_six_addresses() {
+        let hexaddr = HexAddr::origin();
+        let lst: Vec<HexAddr> = hexaddr.within(1).collect();
+        assert_eq!(lst.len(), 6);
+    }
+
+    #[test]
+    fn distance_2_has_18_addresses() {
+        let hexaddr = HexAddr::origin();
+        let lst: Vec<HexAddr> = hexaddr.within(2).collect();
+        assert_eq!(lst.len(), 18);
+    }
+
+    fn address() -> (std::ops::Range<i32>, std::ops::Range<i32>) {
+        (-65536_i32..65535, -65536_i32..65535)
+    }
+
+    proptest! {
+        #[test]
+        fn produces_adjacent_coordinates((x, y) in address(), idx in 0_usize..6) {
+            let coord1 = HexAddr::new(x, y);
+            let lst1: HashSet<HexAddr> = coord1.adjacencies().collect();
+            assert_eq!(lst1.len(), 6);
+
+            let lst1 = lst1.into_iter().collect::<Vec<_>>();
+            let coord2 = &lst1[idx];
+            let lst2: Vec<HexAddr> = coord2.adjacencies().collect();
+            assert!(lst2.contains(&coord1));
+        }
+
+        #[test]
+        fn tests_adjacencies((q, r) in address(), idx in 0_usize..6) {
+            let coord1 = HexAddr::new(q, r);
+            let lst1: Vec<HexAddr> = coord1.adjacencies().collect();
+            assert_eq!(lst1.len(), 6);
+
+            let coord2 = &lst1[idx];
+            assert!(coord2.is_adjacent(&coord1));
+            assert!(coord1.is_adjacent(&coord2));
+        }
+
+        #[test]
+        fn measures_distance((q1, r1) in address(),
+                                (q2, r2) in address()) {
+            let hexaddr_1 = HexAddr::new(q1, r1);
+            let hexaddr_2 = HexAddr::new(q2, r2);
+
+            let s1 = -q1 - r1;
+            let s2 = -q2 - r2;
+            let expected = (((q1 - q2).abs() + (r1 - r2).abs() + (s1 - s2).abs()) / 2) as usize;
+            assert_eq!(hexaddr_1.distance(&hexaddr_2), expected);
+            assert_eq!(hexaddr_2.distance(&hexaddr_1), expected);
+        }
+
+        #[test]
+        fn calculates_distance((q, r) in address(), distance in 0_usize..6) {
+            let hexaddr = HexAddr::new(q, r);
+            let en_distancaj_hexaddr: Vec<HexAddr> = hexaddr.within(distance).collect();
+
+            let expected_cnt = ((0..distance+1).map(|v| v * 6).fold(0, |acc, val| acc + val)) as usize;
+            assert_eq!(en_distancaj_hexaddr.len(), expected_cnt);
+            for c in en_distancaj_hexaddr {
+                assert!(c.distance(&hexaddr) <= distance as usize);
+            }
+        }
+    }
+}
diff --git a/coordinates/src/lib.rs b/coordinates/src/lib.rs
new file mode 100644
index 0000000..6e34e58
--- /dev/null
+++ b/coordinates/src/lib.rs
@@ -0,0 +1,22 @@
+/*
+Copyright 2022, Savanni D'Gerinel <savanni@luminescent-dreams.com>
+
+This file is part of Koordinatoj.
+
+Lumeto is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
+
+Lumeto is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along with Lumeto. If not, see <https://www.gnu.org/licenses/>.
+*/
+use thiserror;
+
+#[derive(Debug, thiserror::Error)]
+pub enum Error {
+    #[error("La enhavita koordinato ne estas valida en ĉi-tiu sistemo")]
+    InvalidCoordinate,
+}
+
+mod hex;
+
+pub use hex::HexAddr;
diff --git a/flake.lock b/flake.lock
index 869d819..fcc38c1 100644
--- a/flake.lock
+++ b/flake.lock
@@ -17,11 +17,11 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1672335022,
-        "narHash": "sha256-417aTRDZpob/UNsA4A0ilBUBQ0H8u+Wx9+OJAAygufQ=",
+        "lastModified": 1672580127,
+        "narHash": "sha256-3lW3xZslREhJogoOkjeZtlBtvFMyxHku7I/9IVehhT8=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "88eaf4a29b5b87a5f83fab413caba24cb13633f0",
+        "rev": "0874168639713f547c05947c76124f78441ea46c",
         "type": "github"
       },
       "original": {
@@ -52,7 +52,7 @@
         "nixpkgs": "nixpkgs_2"
       },
       "locked": {
-        "narHash": "sha256-ruR2xo30Vn7kY2hAgg2Z2xrCvNePxck6mgR5a8u+zow=",
+        "narHash": "sha256-VCSmIYJy/ZzTvEGjdfITmTYfybXBgZpMjyjDndbou+8=",
         "type": "tarball",
         "url": "https://github.com/oxalica/rust-overlay/archive/master.tar.gz"
       },