What is "negative crystal"

Negative \Neg"a*tive\ (n[e^]g"[.a]*t[i^]v), a. [F. n['e]gatif, L. negativus, fr. negare to deny. See Negation.]

1. Denying; implying, containing, or asserting denial, negation or refusal; returning the answer no to an inquiry or request; refusing assent; as, a negative answer; a negative opinion; -- opposed to affirmative.

   If thou wilt confess, Or else be impudently negative.
   --Shak.

   Denying me any power of a negative voice.
   --Eikon Basilike.

   Something between an affirmative bow and a negative shake.
   --Dickens.

2. Not positive; without affirmative statement or demonstration; indirect; consisting in the absence of something; privative; as, a negative argument; negative evidence; a negative morality; negative criticism.

   There in another way of denying Christ, . . . which is negative, when we do not acknowledge and confess him.
   --South.

3. (Logic) Asserting absence of connection between a subject and a predicate; as, a negative proposition.

4. (Photog.) Of or pertaining to a picture upon glass or other material, in which the lights and shades of the original, and the relations of right and left, are reversed.

5. (Chem.) Metalloidal; nonmetallic; -- contrasted with positive or basic; as, the nitro group is negative. Note: This word, derived from electro-negative, is now commonly used in a more general sense, when acidiferous is the intended signification. Negative crystal.

   1. A cavity in a mineral mass, having the form of a crystal.

   2. A crystal which has the power of negative double refraction. See refraction.

      negative electricity (Elec.), the kind of electricity which is developed upon resin or ebonite when rubbed, or which appears at that pole of a voltaic battery which is connected with the plate most attacked by the exciting liquid; -- formerly called resinous electricity. Opposed to positive electricity. Formerly, according to Franklin's theory of a single electric fluid, negative electricity was supposed to be electricity in a degree below saturation, or the natural amount for a given body. See Electricity.

      Negative eyepiece. (Opt.) see under Eyepiece.

      Negative quantity (Alg.), a quantity preceded by the negative sign, or which stands in the relation indicated by this sign to some other quantity. See Negative sign (below).

      Negative rotation, right-handed rotation. See Right-handed, 3.

      Negative sign, the sign -, or minus (opposed in signification to +, or plus), indicating that the quantity to which it is prefixed is to be subtracted from the preceding quantity, or is to be reckoned from zero or cipher in the opposite direction to that of quanties having the sign plus either expressed or understood; thus, in a - b, b is to be substracted from a, or regarded as opposite to it in value; and -10[deg] on a thermometer means 10[deg] below the zero of the scale.

n. 1 (context optics English) A uniaxial crystal, such as one of calcite, in which the extraordinary wave travels faster than the ordinary wave 2 A crystal that contains a cavity