Calcium carbonate- CaCO3 may also contain other minerals  寒 水 石 Hán shuǐ shí   Calcite,  Glauberitum, gypsum rubrum, and crystalline mirabilite  
Nature- cold   FLAVOR:  Acrid, salty    CHANNEL: Stomach, Kidney, Heart
FUNCTIONS
GROUP: Clearing Internal Heat- Reducing Fire
1. Drains Fire and expels Summer Heat.[2]
2. Applied topically for burns and sores.[2]
ACTIONS
INDICATIONS
1. High fever: irritability, thirst, T- yellow coating associated with Summer Heat Warm febrile disease.[2]
2. Used topically for burns, sore throat and oral ulcers.[2]
CONTRAINDICATIONS: : Spleen/Stomach weak and deficiency.[1]
COMBINATIONS
CONTRAINDICATIONS: Deficiency of Spleen or Stomach Cold.[2]
 PREPARATIONS: 9-30 g.[2] Used as a powder, especially for external application.[2]

References
Inner Path can not take any responsibility for any adverse effects from the use of plants. Always seek advice from a professional before using a plant medicinally.
Research

Meta-analysis of calcium bioavailability: a comparison of calcium citrate with calcium carbonate.
Sakhaee K, Bhuket T, Adams-Huet B, Rao DS.
Abstract
OBJECTIVE:
To perform a meta-analysis of data from available published trials comparing the bioavailability of calcium carbonate with that of calcium citrate.
|DATA SOURCES:
The whole set was comprised of 15 studies involving 184 subjects who underwent measurement of calcium absorption from calcium carbonate and calcium citrate. Category A excluded four studies for lack of physiological relevance, use of a mixed preparation with low content of calcium carbonate, or wide variability in results. Category B was comprised of five studies (from Category A) involving 71 subjects who took calcium supplements on an empty stomach. Category C was comprised of six studies (from Category A) involving 65 subjects who took calcium preparations with meals.
METHOD:
The meta-analysis of calcium absorption data from calcium carbonate and calcium citrate, with calculation of effect size and 95% confidence intervals.
RESULTS:
Calcium absorption from calcium citrate was consistently significantly higher than that from calcium carbonate by 20.0% in the whole set, by 24.0% in Category A, by 27.2% on an empty stomach, and by 21.6% with meals.
CONCLUSION:
Calcium citrate is better absorbed than calcium carbonate by approximately 22% to 27%, either on an empty stomach or co-administered with meals.
PMID: 11329115 Am J Ther. 1999 Nov;6(6):313-21. ncbi.nlm.nih.gov

Dose dependency of calcium absorption: a comparison of calcium carbonate and calcium citrate.
Harvey JA, Zobitz MM, Pak CY.
Abstract
Calcium supplementation is recommended as a prophylaxis against bone loss. This study was performed to determine the dose dependency of calcium absorption in an attempt to derive an optimum dose schedule. Using the well-described oral calcium load technique, we measured the calcium absorption from three different calcium doses (0.5, 1.0, and 2.0 g) of both calcium carbonate and calcium citrate administered to 21 normal subjects (4 men and 17 women, 22-60 years). Nine subjects underwent two additional loads with 0.2 g of elemental calcium as calcium carbonate and as calcium citrate. The intestinal calcium absorption from calcium carbonate and calcium citrate was estimated from the rise in urinary calcium following oral ingestion of the respective calcium salt. The increment in urinary calcium post-load, reflective of intestinal calcium absorption, rose rapidly from 0 to 0.5 g calcium loads with only slight subsequent increases from the 0.5 g to 2.0 g calcium doses. Thus, results indicate that 0.5 g of calcium is the optimum dose of either calcium salt. Moreover, the increment in urinary calcium post-load was higher from calcium citrate than from calcium carbonate at all four dosage levels. The increment in urinary calcium (during the second 2 hr) following calcium citrate load (0.5 g calcium) was 0.104 +/- 0.096 mg/dl glomerular filtrate (GF), which was higher than that of 0.091 +/- 0.068 mg/dl GF obtained from 2.0 g calcium as calcium carbonate. These results confirm the superior calcium bioavailability from calcium citrate as compared with calcium carbonate.(ABSTRACT TRUNCATED AT 250 WORDS).
PMID: 3213620 DOI: 10.1002/jbmr.5650030303 J Bone Miner Res. 1988 Jun;3(3):253-8. ncbi.nlm.nih.gov

The effect of calcium carbonate and calcium citrate on the absorption of zinc in healthy female subjects.
Argiratos V, Samman S.
Abstract
OBJECTIVES:
The aim of this study was to determine the effect of calcium carbonate and calcium citrate on zinc absorption.
DESIGN:
The zinc tolerance test (ZTT), which is the plasma zinc response to an oral zinc challenge, was used to quantitate zinc absorption. A physiological test dose of zinc (4.5 mg elemental zinc as 20 mg zinc sulphate) was used. Subjects underwent ZTTs on three separate occasions, each time consuming in random order, either 4.5 mg elemental zinc, zinc with 600 mg elemental calcium as calcium carbonate or zinc with 600 mg elemental calcium as calcium citrate.
SETTING:
Metabolic ward conditions.
SUBJECTS:
Nine, free-living, healthy female subjects recruited from the University population.
INTERVENTIONS:
Blood samples were obtained at 30 min intervals for 4 h postdose.
RESULTS:
The area under the plasma zinc curve (AUC) (mean +/- SEM) following the coingestion of zinc with calcium carbonate (438.4 +/- 129.0 mumol Zn.min/100 g albumin) and calcium citrate (308.0 +/- 110.5) was significantly lower (P < 0.017) than when zinc was ingested alone (1561.7 +/- 240). Urinary excretion of calcium was significantly higher (P < 0.017) at 4 h after supplementation with calcium citrate (0.83 +/- 0.12 mumol Ca/mumol creatinine) compared with calcium carbonate (0.40 +/- 0.11).
CONCLUSIONS:
The decrease in zinc absorption following the ingestion of zinc with different forms of calcium suggests that an antagonistic competition occurred between the minerals and that elemental calcium is the inhibiting factor.
PMID: 8194505 Eur J Clin Nutr. 1994 Mar;48(3):198-204. ncbi.nlm.nih.gov