Flower Cave, Texas, USA
Speleothems: Cave flowers
Frequency: Very Rare
Other geologic settings: The cave is developed in the Santa Elena limestone, which is a massive, thickly bedded, dense, cherty, grey, escarpment-forming limestone.
Location within cave: Once entering the cave you must navigate through a crawl space for 15m. This crawlway terminates into a chamber 2m in height and 3m in diameter. On the back wall of this room are numerous cave flowers protruding from the bedrock, along a horizontal plane.
First description of cave occurrence: Hill, C., Ewing, R. 1977. Darapskite, Na3(NO3)(SO)42-·H2O, A New Occurence in Texas. MIneralogical Magazine 41: 548-550
First description of non-cave occurrence: Dietze, A. 1891. Einige neue chilenische Mineralie. Zeitschrift für Kristallographie, Mineralogie und Petrographie, Leipzig 19: 445-451
Depth: 2
Water: Yes
Type of rock: Limestone
Age: Lower Cretaceous
Group: Nitrates
Chemical formula: Na3(SO)42-NO3)·H2O
[According to the official IMA-CNMNC List of Mineral Names (http://nrmima.nrm.se/imalist.htm)]
Deposition and stability: The cave flowers have formed by precipitation of soluble salts when ground water moving along bedding planes reaches the surface. Each precipitated layer is subsequently forced outward parallel to the bedrock wall by the subsequent precipitating solutions.
Color: Colorless
Luster: Vitreous
Diagnostic features: very soluble in water
X-ray diffraction
Chemical analysis: (wt%): Na+: 32.85; K+: 0.016; Ca2+: 0.93; Fe2+: .028; Mg2+: 0.054; Sr2+: 0.011; Mn2+: 0.005; Ti4+: 0.120; Al3+: 0.011; NO3-: 12.80; Cl-: 28.00; SO24-: 21.53; CO23-: 0.90; PO34-: 0.01; H2O 3.44; (total%) 100.72
Mineral assemblage: + mirabilite,epsomite,gypsum, and halite (all have been reported as cave flowers)
Cell parameter b (Å): 6.870(2)
Cell parameter c (Å): 5.186(1)
Cell parameter β (Å): 101degrees 46.1(5)
Crystal size: 0.2mm in length
Translucent, prismatic crystals are shown under plane polarized light
Twins: Polysynthetic twinning parallel to 100 is rare.