Silicate carbonate

The silicate carbonates are double salts that contain both silicate and carbonate in their formula. Most compounds are natural minerals containing calcium or rare earth elements. However, some have been made experimentally. Silicate carbonate minerals can be formed in limestone metamorphosed by heating from igneous intrusions. Scawtite forms where the activity of calcium is high compared to H⁺. Spurrite forms in a limited range of calcium activity and high silica activity. In magma, a carbonate rich melt is immiscible with a silicate melt.

Structures

Silicate carbonates contain carbonate triangles, and silicate tetrahedrons, SiO₄. Tillyite contains disilicate Si₂O₇ units.

Properties

List

formula	name	structure	density	comment	ref
Ca₄Si₂O₆₂	fukalite
Ca₅₂	spurrite
Ca₅₂	tilleyite	monoclinic =7.582 Å, b=10.265 Å, c =15.030 Å β=103.99°
Ca₅₂	post-Tilleyite
Ca₆_1.58_0.21₇Cl_0.5_0.08 _0.42	deferenite
Ca₇₃	galuskinite
Ca₇·2H₂O	scawtite
Ca₃Si₆•12H₂O	thaumasite	Hexagonal a = 11.03, c = 10.4
Na₇Ca1.5•2H₂O	cancrinite	hexagonal a = 12.67 c = 5.15
	meionite	tetragonal I4/m a = 12.179, c = 7.571, Z = 2
₄Al₆Si₆O₂₄	silvialite
	scapolite
K₂Ca		P6₃22 a = 5.0479 c = 17.8668		artificial
KNa₄Ca₄₄F·H₂O	carletonite
Y₂	iimoriite-	triclinic P1_ a=6.549 b=6.629 c=6.4395 α=116.36° β=92.56° γ=195.507°
Ca₂Y₂₄·H₂O	kainosite
Ca₄Y₄₄₆·7H₂O	caysichite
K₅Na₅Y₁₂₁₄₈₂·8H₂O	ashcroftine
Na₂Ba₂FeTi ₃F	bussenite
Ba₆Fe₃₂Cl₃·H₂O	fencooperite
La₂Mn	alexkuznetsovite-	P2₁/c ''Z = 4 a'' = 6.5642 b = 6.7689 c = 18.721 Å, β = 108.684° V = 788.00 Å³
La₂Fe²⁺	biraite-	P2₁/c Z = 4 a = 6.566 b = 6.767 c = 18.698 Å, β = 108.95° V = 785.7 Å³
Ce₂Mn	alexkuznetsovite-	P2₁/c ''Z = 4 a'' = 6.5764 b = 6.7685 c = 18.749 Å, β = 108.672° V =790.7 Å³
Ce₂Fe²⁺	biraite	monoclinic P2₁/c, a 6.505 b 6.744 c 18.561 β=108.75°
Na₂Ce₂TiO₂₂	tundrite
	iimorite
Pb_19.4Na_1.9₉_12.7				artificial
Cu₄Pb₄OH)₄Cl	ashburtonite