Cyclosilicates
Beryl: Be{{< sub 3 >}}Al{{< sub 2 >}}Si{{< sub 6 >}}O{{< sub 18 >}}.
Tourmaline single crystal and tourmalines in quartz: NaMg{{< sub 3 >}}Al{{< sub 5 >}}B{{< sub 3 >}}Si{{< sub 6 >}}O{{< sub 27 >}}(OH){{< sub 4 >}}.
Radiating acicular tourmaline crystals and tourmaline crystal in quartz: NaMg{{< sub 3 >}}Al{{< sub 5 >}}B{{< sub 3 >}}Si{{< sub 6 >}}O{{< sub 27 >}}(OH){{< sub 4 >}}.
