23 GARDEN LEVEL EXHIBITS Galena Crystals Galena is the most common of the lead minerals It frequently contains enough silver to be mined as a silver ore too S of t and heavy it is dark lead gray with a metallic luster It typically tak es the form of cubeshaped crystals These large cubic g alena crystals from the R oyal Flush mine S ocor ro County New Mexico were deposited from mineralizing fuids that mo ved into limestone layer s through fractures and fault z ones The limestone has been par tially altered to clay minerals The clear stubby crystals are smok y quar tz In addition to being a source of lead g alena has been used as the radio crystal in crystaldetector radio recei ver s Gift from James McGlasson Colorado School of Mines Golden Colorado Silicifed W ood This specimen from the Upper Cretaceous W ayan F ormation in W ayan Idaho is a cross section through the trunk of a gi ant tree fern T empsk ya The tree ferns grew to several meter s 1 01 2 f t in height with trunks up to 40 cm 1 6 in in diameter The internal structure of the plant is well preserved Gift from the Department of Geolog y Idaho State Univ ersity P ocatello through H Thomas Ore Malac hit e on Nativ e Copper This specimen is made up almost entirely of nati ve copper but w as co vered with a thin coating of green malac hite and oth er minerals when the copper o xidiz ed Gift from W illiam J LeV eque Claremont California Copper Dr ag on This fne cluster of nati ve crystalline copper is thinly coated with the red brown dust of cuprite copper o xide The bluegreen color is a mixture of other copper minerals T o some the specimen appear s to resemble a dragon The specimen is from the S outh Pit Chino mine S anta Rita New Mexico known for ruby red cuprite crystals scat tered across nati ve copper Gift from Gregory E McK elv e y Bear Creek Mining Compan y T ucson Arizona Linar it e on Fluor it e Deep blue linarite crystals and gray fuorite crystals form this roc k from Blan c hard mine in S ocor ro County New Mexico S ome samples of linarite fuo resce The word fuorescence is deri ved from fuorite s c haracteristic violet blue luminescence under ultraviolet light Fluorescent minerals emit light when exposed to ultraviolet light of cer tain w avelengths These minerals glow in the dark under blac k light Their luminescence is caused by the motion of electrons in their atomic structuresthe minerals absorb energy from light The absorbed energy temporarily boosts electrons in the minerals to higher energy levels As the electrons return to their normal energy levels the extra energy is released in the form of light Linarite is named for its disco very site near Linares Spain