Missouri Rocks and Minerals

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PictureNameColorLusterMohsTenacitySpecific GravityCrystal HabitOther Characteristics
BariteColorless, white, and light shades of blue, yellow, red; transparent to translucent; commonly stained superficially with red iron oxideVitreous, sometimes pearly in part3-3.5Brittle4.5 Commonly in divergent groups of tabular orthorhombic crystals that are called crested barite or barite roses; less commonly in stouter prismatic (pseudo-cubic) orthorhombic crystalsNontoxic and low solubility
CalciteTypically colorless or white - may have shades of various colorsVitreous to pearly on cleavage surfaces3Brittle2.71Crystalline, granular, stalactitic, concretionary, massive, rhombohedralMay fluoresce red, blue, yellow, and other colors under either SW and LW UV; phosphorescent
Soluble in dilute acids
GalenaLead gray and silveryMetallic on cleavage planes2.5-2.75Brittle7.2–7.6Cubes and octahedra, blocky, tabular and sometimes skeletal crystalsNatural semiconductor
LimoniteVarious shades of brown and yellowEarthy4-5.5Soft2.9-4.3Fine grained aggregate, powdery coatingNo cleavage
MagnetiteBlack, gray with brownish tint in reflected sunMetallic5.5-6.5Brittle5.17–5.18Octahedral, fine granular to massiveDissolves slowly in hydrochloric acid
MarcasitePale brass-yellow, tin-white on fresh exposuresMetallic6-6.5Brittle4.875Typically tabular, curved faces common, stalactitic, reniform
Missouri Lace AgateBandedWaxy6.5-72.58-2.64Cryptocrystalline silicaTranslucent
PyritePale brass-yellow reflective; tarnishes darker and iridescentMetallic, glistening6-6.5Brittle4.9-5.10Pale brass-yellow reflective; tarnishes darker and iridescentInsoluble in water
QuartzColorless through various colors to blackVitreous – waxy to dull when massive7Brittle2.656-sided prism ending in 6-sided pyramid (typical), drusy, fine-grained to microcrystalline, massiveInsoluble at standard temp and pressure
Lattice: hexagonal, Piezoelectric, may be triboluminescent, chiral
Sources: MODNR; Mindat; Wikipedia

Igneous Rocks

GraniteDue to differences in mineralogical composition and differences in cooling rates, the colors and textures of the granites are quite differentFelsic
Potassium feldspar
Plagioclase feldspar
RhyoliteReferred to by stone producers as a “traprock,” Missouri rhyolite varies in color from light gray through pink and red to dark purplish-red
Sometimes it has a distinct banded pattern
Igneous quartz
Alkali feldspar
Sources: MODNR; Mindat; Wikipedia

Metamorphic Rocks

PictureNameDescriptionCompositionSecondary Composition
QuartziteGenerally grey or pink, has a banded appearance, and is made up of granular mineral grainsQuartz
Sources: MODNR; Mindat; Wikipedia

Sedimentary Rocks

ChertWhite, tan or light gray
Red, brown, reddish-brown and yellowish-brown varieties are called jasper
Black and dark gray specimens are known as flint
Mottled and pink types are called Mozarkite
Some banded varieties have found a home in the agate family
Leaves residue
ConglomerateConsists of pieces known as clasts of pre-existing rocks, pebbles, cobble or boulders that are naturally cemented together in a finegrained matrix of sand, silt, calcium carbonate, iron oxide, silica or clay
FireclayBuff, yellow, red, green or brown
Good, useable fireclay is usually white, cream-colored, gray, or almost black
Aluminum oxide
LimestoneTypically white, gray or tan; can also occur in shades of yellow, green, blue, brown, pink. red, or blackCalcite
MozarkiteMottled pink and white version of chertSilica
Sources: MODNR; Mindat; Wikipedia


BivalvesShells of bivalves are composed of two separate valves, typically about the same size. They often nearly mirror one another. The valves are bound together with a bendable ligament (band of tissue) along a hinge line on the dorsal (back) side of the shell
BlastoidsBlastoids are related closely to another group of similar-looking stemmed echinoderms called crinoids. Blastoids differ from crinoids in having a more highly developed five-sided (pentamerous) symmetry and specialized anatomical features that are lacking in crinoids
Also, blastoids tended to be smaller in size and shorter stemmed
BrachiopodsThe outer surface of brachiopod shells can be smooth, ribbed, ridged or spiny
The inner surface is mostly smooth with ridges, muscle scars and other markings that are used in classification and identification
Conulariid JellyfishConulariid periderms have a four-sided pyramid shape that typically is elongated from apex to opposite end (aperture)
CrinoidMost often, crinoid fossils are found in limestone as dismembered pieces with their individual hard parts preserved
GastropodsShells are made of calcium carbonate in the form of the minerals aragonite or calcite or both
Shells can be uncoiled or coiled. Uncoiled shells are cap-shaped to horn-shaped
Coiled shells wrap around themselves spirally as they grow
NautiloidRigid, one-piece, external, calcium carbonate shells
StarfishFossils of whole starfish are rare
Regular EchinoidsIndividual spines and individual ossicles are the typical finds while fossils of whole echinoids are rare
TrilobiteThree-lobed construction of their bodies, with a central (axial) lobe flanked by two side (pleural) lobes. Their bodies consisted of a head (cephalon) with two compound eyes similar to present-day insects, a body (thorax) and a tail (pygidium)
Sources: MODNR; Mindat; Wikipedia