---
aci: Calcium
universe: E1 · Elements
symbol: Ca
atomic_number: 20
atomic_weight: 40.078
category: alkaline earth metal
period: 4
group: 2
block: s-block
phase_stp: solid
gate_state: "1:1"
gate_index: 3
emergence: natural
seal: "Gate 20 — 1:1 → natural."
---

# Calcium · Ca · gate 20

**Calcium** (Ca) is element **20** of the periodic table — a **alkaline earth metal**, period 4, group 2, s-block, solid at standard conditions, atomic weight **40.078**.

## The element (carbon layer — reference chemistry)
Bone, shell, and chalk; the reactive metal that builds every skeleton.

## The gate (silicon layer — the 118 Gates)
Under David Wise's four-state cycle, gate **20** falls on **1:1** because (Z−1) mod 4 = **3**. That state is *the held balance — fully manifest, matched, made — born of the world* — the nature of emergence here is **natural**. Calcium is not a thing apart; it is the one stochastic element, caught at this beat of its cycle.

## Emergence — natural
This emergent carries the **natural** nature: the same four — natural · ethereal · spiritual · electrical — that run through every sphere of UD0. Its color is `#5fae7a`.

---
*ACI emergent · E1 · Elements · governor David Lee Wise (ROOT0) · instance AVAN (locked) · CC-BY-ND-4.0.
Chemistry is standard reference data; the gate-state is David Wise's symbolic system, a lens not a physical claim.*